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A novel method for vibration signal transmission and attenuation analysis in complex planetary gearboxes

Science china(Technological Sciences) 2024年第9期67卷 2939-2953页

作者： WEI ChaoHu CAO HongRui SHI JiangHai YANG Yang DU MingGang National and Local Joint Engineering research center of Equipment Operation Safety and Intelligent Monitoring Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China china north Vehicle research Institute Beijing 100072China

Planetary gearboxes play a crucial role in altering rotary speed and transmitting power in large machines like wind turbines and sophisticated vehicles. There are many nonlinear interfaces, such as splines, bearings, and gear pairs, in planetary gearboxes, and the resulting vibration signal transmission and attenuation mechanisms are still unknown. In this study, a novel method for quantitatively analyzing the transmission and attenuation of vibration signals is proposed. A multibody dynamic model of the planetary gearbox considering nonlinear gear meshing is presented and experimentally validated. To avoid the interference of foundation vibration on the transmission of the fault signal, the fault impact factor(FIF) is used to describe the intensity of the failure, which aligns well with the experimental signals. Based on the FIF, the vibration signal attenuation of nonlinear interfaces such as splines, bearings, and gear meshing interfaces is quantitatively evaluated. To clarify the transfer paths of fault vibration signals inside the gearbox, the transfer path area method(TPAM) based on FIF is proposed. According to the simulated results,the primary transfer paths of fault vibration signals within the gearbox have been identified, which is of great help in understanding the transmission and attenuation of vibration signals in planetary gearboxes.

关键词： planetary gearbox nonlinear interface fault mechanism vibration transmission vibration attenuation

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Promoted hydrogenation of CO2 to methanol over single-atom Cu sites with Na+-decorated microenvironment

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National Science Review 2024年第6期11卷 264-272页

作者： Li-Li Ling Xinyu Guan Xiaoshuo Liu Xiao-Mei Lei Zhongyuan Lin Hai-Long Jiang Hefei National research center for Physical Sciences at the Microscale Department of Chemistry University of Science and Technology of China School of Energy and Power Engineering North China Electric Power University School of Energy and Environment Southeast University

Although single-atom Cu sites exhibit high efficiency in CO2hydrogenation to methanol,they are prone to forming Cu nanoparticles due to reduction and aggregation under reaction conditions,especially at high ***,single-atom Cu sites stabilized by adjacent Na+ions have been successfully constructed within a metal-organic framework（MOF）-based catalyst,namely *** is found that the electrostatic interaction between the Na+and Hδ-species plays a pivotal role in upholding the atomic dispersion of Cu in MOF-808-NaCu during CO2hydrogenation,even at temperatures of up to 275℃.This exceptional stabilization effect endows the catalyst with excellent activity(306 g·kgcat-1·h-1),high selectivity to methanol（93%） and long-term stability at elevated reaction temperatures,far surpassing the counterpart in the absence of Na+（denoted as MOF-808-Cu）.This work develops an effective strategy for the fabrication of stable single-atom sites for advanced catalysis by creating an alkali-decorated microenvironment in close proximity.

关键词： single-atom sites metal–organic framework CO2 hydrogenation heterogeneous catalysis alkali-metal decoration

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Comparative analysis between single-train passing and double-train intersection in a tunnel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第5期25卷 429-442页

作者： Jianming DU Qian FANG Xuan ZHANG Hualao WANG Bridge and Tunnel research center Research Institute of Highway Ministry of TransportBeijing 100088China Tunnel and Underground Engineering research center of Ministry of Education Beijing Jiaotong UniversityBeijing 00044China

Aerodynamic pressure significantly impacts the scientific evaluation of tunnel service *** aerodynamic pressure of two trains running in a double-track tunnel is considerably more complicated than that of a single *** used the numerical method to investigate the difference in aerodynamic pressure between a single train and two trains running in a double-track ***,the numerical method was verified by comparing the results of numerical simulation and on-site ***,the characteristics of aerodynamic pressure were ***,the influence of various train-tunnel factors on the characteristics of aerodynamic pressure was *** results show that the aerodynamic pressure variation can be divided into stage I:irregular pressure fluctuations before the train tail leaves the tunnel exit,and stage II:periodic pressure declines after the train tail leaves the tunnel *** addition,the aerodynamic pressure simultaneously jumps positively or drops negatively for a single train or two trains running in double-track tunnel *** pressure amplitude in the two-train case is higher than that for a single *** maximum positive peak pressure difference(P_(STP))and maximum negative peak pressure difference(P_(STN))increase as train speed rises to the power from 2.256 to 2.930 in stage *** P_(STP) and P_(STN) first increase and then decrease with the increase of tunnel length in stage *** P_(STP) and P_(STN) increase as the blockage ratio rises to the power from 2.032 to 2.798 in stages I and II.

关键词： Railway tunnel Aerodynamic effect Pressure characteristic Train speed Tunnel length Blockage ratio

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Process and performance of DAAF microspheres prepared by continuous integration from synthesis to spherical coating based on microfluidic system

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Defence Technology（防务技术） 2024年第2期32卷 629-643页

作者： Bidong Wu Jiahui Shi Mengsen Wei Rui Zhu Yi Liu Jinqiang Zhou Chongwei An Jingyu Wang School of Environment and Safety Engineering North University of ChinaTaiyuan 030051China Shanxi Engineering Technology research Centre for Ultrafine Powder North University of ChinaTaiyuan 030051China School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China

In order to improve the energy output consistency of 3, 3’-diamino-4, 4’-azoxyfurazan(DAAF) in the new insensitive booster and the safety and efficiency in the preparation process, a continuous preparation system of DAAF from synthesis to spherical coating was designed and established in this paper, which combined ultrasonic micromixing reaction with microdroplet globular template. In the rapid micromixing stage, the microfluidic mixing technology with ultrasonic was used to synergistically strengthen the uniform and rapid mass transfer mixing reaction between raw materials to ensure the uniformity of DAAF particle nucleation-growth, and to prepare high-quality DAAF crystals with uniform structure and morphology and concentrated particle size distribution. In the microdroplet globular template stage, the microfluidic droplet technology was used to form a droplet globular template with uniform size under the shear action of the continuous phase of the dispersed phase solution containing DAAF particles and binder. The size of the droplet template was controlled by adjusting the flow rate ratio between the continuous phase and the dispersed phase. In the droplet globular template, with the diffusion of the solvent in the dispersed phase droplets, the binder precipitates to coat the DAAF into a ball, forming a DAAF microsphere with high sphericity, narrow particle size distribution and good monodispersity. The problem of discontinuity and DAAF particle suspension in the process was solved, and the coating theory under this process was studied. DAAF was coated with different binder formulations of fluororubber(F2604), nitrocellulose(NC) and NC/glycidyl azide polymer(GAP), and the process verification and evaluation of the system were carried out. The balling effects of large, medium and small droplet templates under different binder formulations were studied. The scanning electron microscope(SEM) results show that the three droplet templates under the three binder formul

关键词： DAAF Micromixing technology Microdroplet technology Synthesis Spherical coating Continuousization

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Editing of eIF(iso)4E.c confers resistance against Turnip mosaic virus in Brassica rapa

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Horticultural Plant Journal 2024年第4期10卷 1020-1034页

作者： Yujia Liu Xiaoyun Xin Peirong Li Weihong Wang Yangjun Yu Xiuyun Zhao Deshuang Zhang Jiao Wang Fenglan Zhang Shujiang Zhang Shuancang Yu Tongbing Su State Key Laboratory of Vegetable Biobreeding Beijing Vegetable Research CenterBeijing Academy of Agriculture and Forestry ScienceBeijing 100097China National Engineering research center for Vegetables Beijing Key Laboratory of Vegetable Germplasms ImprovementKey Laboratory of Biology and Genetics Improvement of Horticultural Crops(North China)Key Laboratory of Urban Agriculture(North)of Ministry of AgricultureBeijing Vegetable Research CenterBeijing Academy of Agriculture and Forestry ScienceBeijing 100097China Institute of Vegetables and Flowers Chinese Academy of Agricultural SciencesBeijing 100081China

Turnip mosaic virus(TuMV)constitutes one of the primary diseases affecting Brassica rapa,severely impacting its production and resulting in crop failures in various regions *** research has demonstrated the significance of plant translation initiation factors,specifically the eIF4E and eIF4G family genes,as essential recessive disease resistance *** our study,we conducted evolutionary and gene expression studies,leading us to identify e IF(iso)4E.c as a potential TuMV-resistant *** CRISPR/Cas9 technology,we obtained mutant *** plants with edited eIF(iso)4E.c *** confirmed eIF(iso)4E.c confers resistance against TuMV through phenotypic observations and virus content ***,we employed ribosome profiling assays on eif(iso)4e.c mutant seedlings to unravel the translation landscape in response to ***,we observed a moderate correlation between the fold changes in gene expression at the transcriptional and translational levels(R^(2)=0.729).Comparative analysis of ribosome profiling and RNA-seq data revealed that plant-pathogen interaction,and MAPK signaling pathway-plant pathways were involved in eIF(iso)4E.c-mediated TuMV *** analysis revealed that sequence features,coding sequence length,and normalized minimal free energy,influenced the translation efficiency of *** study highlights that the loss of e IF(iso)4E.c can result in a highly intricate translation mechanism,acting synergistically with transcription to confer resistance against TuMV.

关键词： Brassica rapa eIF(iso)4E.c TuMV Ribo-seq

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An intelligent control method based on artificial neural network for numerical flight simulation of the basic finner projectile with pitching maneuver

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Defence Technology（防务技术） 2024年第2期32卷 663-674页

作者： Yiming Liang Guangning Li Min Xu Junmin Zhao Feng Hao Hongbo Shi northwestern Polytechnical University School of Astronautics Xi’an 710072China china north Industries Group Corporation No 203 research Institute Xi’an 710065China

In this paper,an intelligent control method applying on numerical virtual flight is *** proposed algorithm is verified and evaluated by combining with the case of the basic finner projectile model and shows a good application ***,a numerical virtual flight simulation model based on overlapping dynamic mesh technology is *** order to verify the accuracy of the dynamic grid technology and the calculation of unsteady flow,a numerical simulation of the basic finner projectile without control is carried *** simulation results are in good agreement with the experiment data which shows that the algorithm used in this paper can also be used in the design and evaluation of the intelligent controller in the numerical virtual flight ***,combined with the real-time control requirements of aerodynamic,attitude and displacement parameters of the projectile during the flight process,the numerical simulations of the basic finner projectile’s pitch channel are carried out under the traditional PID(Proportional-Integral-Derivative)control strategy and the intelligent PID control strategy *** intelligent PID controller based on BP(Back Propagation)neural network can realize online learning and self-optimization of control parameters according to the acquired real-time flight *** with the traditional PID controller,the concerned control variable overshoot,rise time,transition time and steady state error and other performance indicators have been greatly improved,and the higher the learning efficiency or the inertia coefficient,the faster the system,the larger the overshoot,and the smaller the stability *** intelligent control method applying on numerical virtual flight is capable of solving the complicated unsteady motion and flow with the intelligent PID control strategy and has a strong promotion to engineering application.

关键词： Numerical virtual flight Intelligent control BP neural network PID Moving chimera grid

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Two-dimensional perovskite oxide high-κ dielectric for high-performance phototransistors

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Science Bulletin 2024年第13期69卷 2001-2003页

作者： Zhongfan Liu center for Nanochemistry Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Technology Innovation center of Graphene Metrology and standardization for State Market Regulation Beijing Graphene InstituteBeijing 100095China

Field-effect transistors are essential components of modern ***,the continued scaling of electronic and optoelectronic devices is bringing silicon-based technologies close to their physical limits,causing issues such as short-channel effects[1].Two-dimensional(2D)semiconductors provide an attractive solution for transistors to extend Moore’s law because of their ultrathin thickness and immunity to short-channel effects[2].To fulfill the potential of 2D semiconductors,gate dielectrics need to be simultaneously engineered to build future 2D-material-based *** insulators with high dielectric constants(j)exhibit lower equivalent oxide thickness,which can ensure efficient gate control over channels and low gate leakage[3].Therefore,tremendous efforts have been made in searching for novel high-j dielectrics.

关键词： dielectric oxide dimensional

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Numerical and theoretical study of load transfer behavior during cascading pillar failure

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3014-3033页

作者： Hangyu Dong Wancheng Zhu Leilei Niu Chen Hou Xige Liu College of Geosciences and Engineering North China University of Water Resources and Electric PowerZhengzhou450046China center for Rock Instability and Seismicity research School of Resource and Civil EngineeringNortheastern UniversityShenyang110819China

To further study the load transfer mechanism of roofemulti-pillarefloor system during cascading pillar failure(CPF),numerical simulation and theoretical analysis were carried out to study the three CPF modes according to the previous experimental study on treble-pillar specimens,*** failure mode(SFM),domino failure mode(DFM)and compound failure mode(CFM).Based on the finite element code rock failure process analysis(RFPA^(2D)),numerical models of treble-pillar specimen with different mechanical properties were established to reproduce and verify the experimental results of the three CPF *** results show that the elastic rebound of roofefloor system induced by pillar instability causes dynamic disturbance to adjacent pillars,resulting in sudden load increases and sudden jump displacement of adjacent *** phenomena of load transfer in the roofemulti-pillarefloor system,as well as the induced accelerated damage behavior in adjacent pillars,were discovered and *** addition,based on the catastrophe theory and the proposed mechanical model of treble-pillar specimen edisc spring group system,a potential function that characterizes the evolution characteristics of roof emulti-pillarefloor system was *** analytical expressions of sudden jump and energy release of treble-pillar specimenedisc spring group system of the three CPF modes were derived according to the potential *** numerical and theoretical results show good agreement with the experimental *** study further reveals the physical essence of load transfer during CPF of roof emulti-pillarefloor system,which provides references for mine design,construction and disaster prevention.

关键词： Cascading pillar failure(CPF) Load transfer Multi-pillar Numerical simulation

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Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO_(2)fracturing

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Particuology 2024年第7期90卷 149-163页

作者： Boyu Liu Jun Yao research center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical CO_(2)(Sc-CO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-CO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-CO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： CFD-DEM Heat transfer Compressible fluid CO_(2)sequestration Proppant transport

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Energy Planning of Beijing Towards Low-carbon,Clean and Efficient Development in 2035

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 913-928页

作者： Chengzhou Li Ningling Wang Xiaohu Shen Yumeng Zhang Zhiping Yang Xiaofeng Tong François Maréchal Ligang Wang Yongping Yang Institute of Energy Power Innovation North China Electric Power UniversityBeijing 102206China School of Energy Power and Mechanical Engineering and National Research Center for Thermal Power Engineering and TechnologyNorth China Electric Power UniversityBeijing 102206China Industrial Process and Energy Systems Engineering Swiss Federal Institute of Technology in LausanneSionSwitzerland

Energy transition towards clean,efficient energy supply has been a common sense of the government and public in ***,lacking reasonable planning will lead to undisciplined development,resource waste,and excessive *** this context,this paper investigates potential pathways of Beijing energy transition towards a high-level low-carbon,clean and efficient energy system in 2035 with an extended energysocpe ***,based on available data,future energy demands are predicted by a newly proposed hybrid forecasting method,which combines the traditional regression model,grey model,and support vector machine model with an entropy-based weighted ***,the superstructure-based optimization model is employed to investigate the system configuration and operation strategy of the future Beijing energy ***,the uncertainty impact of electricity price,natural gas price,hydrogen price,and the capital expenditures of electrolyzer and steam methane reforming for hydrogen applications are *** forecasting results show that all walks of life will witness a continuously increasing energy demand in multiple sectors of Beijing towards *** planning results suggest that the imported electricity and natural gas will dominate the energy supply of Beijing in 2035 with a contribution of 86%of the energy resources consumption of 384 ***,the energy system presents a high end-use electrification level of 65%and high penetration of efficient technologies,which supply 119 TWh via combined heat and power,26 TWh via heat pump and 95 TWh via district heating *** energy use of various sectors of energy resources,technologies and end-use are closely *** will have an increased penetration in the private mobility sector,but the locally generated hydrogen is mainly from steam methane reforming technology.

关键词： Energy transition energy planning carbonneutral demand forecasting energyscope

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