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Investigation on dynamic characteristics of a rod fastening rotor-bearing coupling system with fixed-point rubbing

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Applied Mathematics and Mechanics(English Edition) 2022年第7期43卷 1063-1080页

作者： yang yang HJOUyang jin ZENG Hui MA Yiren yang Dengqing CAO School of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China Centre for Engineering Dynamics School of EngineeringUniversity of LiverpoolLiverpool L693GHU.K. School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China School of Astronautics Harbin Institute of TechnologyHarbin 150001China

The aim of this paper is to gain insight into the nonlinear vibration feature of a dynamic model of a gas ***,a rod fastening rotor-bearing coupling model with fixed-point rubbing is proposed,where the fractal theory and the finite element method are *** contact analysis,a novel contact force model is introduced in this ***,the Coulomb model is adopted to expound the friction ***,the governing equations of motion of the rotor system are numerically solved,and the nonlinear dynamic characteristics are analyzed in terms of the bifurcation diagram,Poincarémap,and time ***,the potential effects provided by contact degree of joint interface,distribution position,and amount of contact layer are discussed in ***,the contrast analysis between the integral rotor and the rod fastening rotor is conducted under the condition of fixed-point rubbing.

关键词： rod fastening rotor joint interface fixed-point rubbing nonlinear dynamic characteristic

Numerical implementation and evaluation of resolvent-based estimation for space-time energy spectra in turbulent channel flows

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Acta Mechanica Sinica 2020年第4期36卷 775-788页

作者： Bowen yang Guodong jin Ting Wu Zixuan yang Guowei He State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

Resolvent operator has been increasingly used to investigate turbulent flows and develop control ***,Towne et al.(J Fluid Mech 883:A17,2020)proposed a resolvent-based estimation(RBE)method for predicting turbulent statistics in a channel *** this paper,we utilize the RBE method to predict the root-mean-square(RMS)and space-time energy spectra of streamwise velocity fluctuation,where the input is the space-time energy spectra at a reference horizontal plane located in the logarithmic layer and the output is the space-time energy spectra in the buffer *** explicit formulas for the RBE method are given in detail for numerical *** results show the capability of the RBE method in the prediction of the convection velocity and bandwidth of the space-time energy ***,we make a systematic evaluation of the performance of the RBE method by varying the input configurations,including the wall-normal location of the reference plane,the inclusion or exclusion of the pressure as an input variable,the implementation approach of the pressure boundary condition,and the choice of the window *** is found that the results of both RMS velocity and space-time energy spectra obtained from the RBE method are sensitive to the location of the reference ***,the pressure boundary conditions and inclusion of pressure as an input do not cause significant change in the RMS velocity and space-time energy *** it does not influence the prediction of the RMS velocity,a window function is found crucial in the RBE method for the prediction of the space-time energy spectra.

关键词： Space-time energy spectra Turbulent channel flow Resolvent operator

Efficient Two‑Dimensional Perovskite Solar Cells Realized by Incorporation of Ti_(3)C_(2)T_(x) MXene as Nano‑Dopants

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Nano-Micro Letters 2021年第4期13卷 234-246页

作者： Xin jin Lin yang Xiao‑Feng Wang Key Laboratory of Physics and Technology for Advanced Batteries(Ministry of Education) College of PhysicsJilin UniversityChangchun 130012People’s Republic of China

Two-dimensional(2D)perovskites solar cells(PSCs)have attracted considerable attention owing to their excellent stability against humidity;however,some imperfectness of 2D perovskites,such as poor crystallinity,disordered orientation,and inferior charge transport still limit the power conversion efficiency(PCE)of 2D *** this work,2D Ti3C2Tx MXene nanosheets with high electrical conductivity and mobility were employed as a nanosized additive to prepare 2D Ruddlesden–Popper perovskite *** PCE of solar cells was increased from 13.69(without additive)to 15.71%after incorporating the Ti_(3)C_(2)T_(x) nanosheets with an optimized *** improved performance is attributed to the enhanced crystallinity,orientation,and passivated trap states in the 3D phase that result in accelerated charge transfer process in vertical *** importantly,the unencapsulated cells exhibited excellent stability under ambient conditions with 55±5%relative humidity.

关键词： 2D perovskite solar cells Ti_(3)C_(2)T_(x)nanosheets Trap densities Vertical orientation Charge transport

Infrared radiation characteristics of dagger-type hypersonic missile

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Chinese Journal of Aeronautics 2024年第4期37卷 137-150页

作者： Xubo DU Qingzhen yang Haoqi yang jin BAI Yongqiang SHI School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China

Hypersonic vehicles emit strong infrared radiation from their high-temperature exhaust plume and body, which is critical for infrared early warning, tracking, and guidance. In this work, a comprehensive analysis is conducted on the factors involved in air dissociation reaction within the shock layer of hypersonic missile heads, as well as the multi-component afterburning effect of the exhaust plume. A novel Reverse Monte Carlo Method(RMCM) is proposed for infrared radiation calculation, which utilizes two-dimensional Low-Discrepancy Sequences(LDS) to improve computational accuracy. The numerical calculations for a dagger-type missile show that afterburning reactions increase the temperature on the centerline of the outlet exhaust plume by about 1000 K. The total infrared radiation intensity of the missile is the highest in the 1–3 μm band, with the hightemperature wall of the nozzle being the primary source of solid radiation, and gas radiation primarily coming from H_(2)O. The radiation intensity of the missile exhaust plume in the 3–5 μm band is the highest, with radiation sources primarily coming from CO_(2), CO, and HCl. Afterburning reactions of the exhaust plume increase the total infrared radiation intensity of the missile by about 0.7times. These results can provide reference for the detection and guidance of hypersonic missiles.

关键词： Hypersonic vehicles Infrared radiation Monte Carlo methods Low-discrepancy sequences Exhaust plume Afterburning

Residual Stress Relaxation of Thin‑walled Long Stringer Made of Aluminum Alloy 7050‑T7451 under Transportation Vibration

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Chinese Journal of Mechanical Engineering 2020年第3期33卷 150-159页

作者： Yinfei yang Lu jin Jixing Du Liang Li Wei yang Nanjing University of Aeronautics and Astronautics Nanjing 210016China Shenyang Aircraft Corporation Shenyang 110034China.

Thin-walled long stringer made of aluminum alloy 7050-T7451 is prone to deformation during transportation,so a research of residual stress relaxation was launched in this *** transport resonance stress of long stringer was analyzed based on the power spectral density of road transport *** residual stress relaxation experiment of aluminum alloy 7050-T7451 under different equivalent stress levels was designed and carried *** to the amount of residual stress relaxation in the experiment,an analytical model was established with the equivalent stress level *** deflection range of long stringer was evaluated under different damping *** results show that when the equivalent stress exceeds 0.8σ0.2,the residual stress relaxation of the thin-walled samples *** residual stress relaxation increases linearly with the equivalent stress,which is logarithmically related to the loading *** deformation caused by residual stress relaxation of the long stringer is proportional to the square of the length and the bending moment caused by stress rebalance,and inversely proportional to the moment of inertia of the *** the damping ratio decreases from 0.03 to 0.01,the total deflection of the long stringer increases from 0 to above 1.55 mm.

关键词： Aluminum alloy 7050-T7451 Large thin-walled part Transportation process Residual stress Structural deformation

Adaptive median threshold algorithm used in FDIS of DSSS receivers

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Journal of Systems Engineering and Electronics 2013年第1期24卷 11-18页

作者： Weijun yang Chaojie Zhang Xiaojun jin Zhonghe jin Tieshan Yuan Department of Information Science and Electronic Engineering Zhejiang University Micro-Satellite Research Center Zhejiang University

For direct sequence spread spectrum （DSSS） receivers, the capability of rejecting narrow-band interference can be significantly improved by a process of frequency-domain interference suppression （FDIS）. The key issue of this process is how to determine a threshold to eliminate interference in the frequency domain, which has been extensively studied. However, these previous methods are tedious or very complex. A simple and ef- ficient algorithm based on medians is proposed. The elimination threshold is only related to the median by a scale factor, which can be obtained by the numerical analysis. Simulation results show that the algorithm provides excellent narrow-band interfer- ence suppression while only slightly degrading the signal-to-noise ratio （SNR）. A one-pass algorithm using logarithmic segmentation is further derived to estimate medians with low computational complexity. Finally, the FDIS is implemented in a field programmable gate array （FPGA） of Xilinx. Experiments are carried out by connecting the FDIS FPGA to a DSSS receiver, and the results show that the receiver has an effective countermeasure for a 60 dB interference-to-signal ratio （ISR）.

关键词： direct sequence spread spectrum (DSSS) discreteFourier transform (DFT) frequency-domain interference suppres-sion (FDIS) adaptive median threshold one-pass approximatemedians.

LGR4: A new receptor for a stronger bone

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Science China(Life Sciences) 2016年第7期59卷 735-736页

作者： Yunyun jin Yingzi yang Department of Developmental Biology Harvard School of Dental Medicine

Bone formation and remodeling involves production of bone matrix by osteoblasts and its resorption by osteoclasts. Increased osteoclast activity or reduced osteoblast function leads to osteopenic disorders （Kong et al., 1999）. Therefore, it is crucial to understand mechanisms underlying osteoclast regulation. Such understanding will shed light on identify- ing potential therapeutic targets of osteoporosis, a disease caused by too much bone resorption or insufficient bone formation. RANKL-RANK signaling is required for osteo- clast, activating a variety of downstream signaling path- ways. RANK, also known as tumor necrosis factor （TNF） superfamily member 11 （TNFSF11）, has long been consid- ered to be the sole receptor for RANKL, also known as TNFRSFllA. （Hanada et al.. 2011）. In a recent study.

关键词：受体骨质疏松症肿瘤坏死因子破骨细胞成骨细胞信号路径细胞功能细胞活性

Source and Evolution of the Ore-Forming Fluids of Carlin-Type Gold Deposit in the Youjiang Basin,South China:Evidences from Solute Data of Fluid Inclusion Extracts

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Journal of Earth Science 2021年第1期32卷 185-194页

作者： Xiaoye jin Chengfu yang Jianzhong Liu Wu yang School of Earth Resources China University of GeosciencesWuhan 430074China Engineering Technology Innovation Center of Mineral Resources Explorations in Bedrock Zones Ministry of Natural ResourcesGuiyang 550081China Geological Party Guizhou Bureau of Geology and Mineral Exploration&DevelopmentGuiyang 550018China School of Resources and Environmental Engineering Guizhou Institute of TechnologyGuiyang 550003China

The source and evolution of ore-forming fluids is important to understand the genesis of Carlin-type gold *** on the source and evolution of ore fluid components by the con-ventional geochemical methods have long been a challenge due to the very fine-grained nature and complex textures of hydrothermal minerals in these *** this study,we present the crush-leach analyzed solute data of fluid inclusion extracts within quartz,calcite,realgar,and fluorite from the Shuiyindong,Nibao,and Yata gold deposits in the Youjiang Basin,providing new insights into the source and evolution of ore-forming *** results show that the high molar Cl/Br ratios up to 2508 in fluid inclusion extracts are indicative of a contribution of magmatic hydrothermal ***-ids mixing between basinal and magmatic-hydrothermal fluids are evident on the plots of Cl/Br versus Na/K ratios,showing that ore-stage milky quartz near the magmatic-hydrothermal fluids reflects magma origin of the ore-forming fluids,whereas late ore-stage drusy quartz and realgar near the de-fined basinal fluids suggest the later input of basinal fluids in late-ore *** the predominate-ly host rocks in Shuiyindong,Nibao and Yata gold deposit are bioclastic limestone,sedimentary tuff,and calcareous siltstone,respectively,the solute data of fluid inclusion extracts records they underwent the similar fluid-rocks reactions between the Na-rich magmatic hydrothermal fluids and the Ca-and Mg-rich host *** study highlights the solute data of fluid inclusion extracts obtained by crush-leach analyses have the potential to fingerprint the source and evolution of ore-forming fluids of the Carlin-type gold deposit.

关键词： solute data fluid inclusion source and evolution of ore-forming fluids Carlin-type gold deposit Youjiang Basin

DOA estimation for attitude determination on communication satellites

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Chinese Journal of Aeronautics 2014年第3期27卷 670-677页

作者： yang Bin He Feng jin jin Xiong Huagang Xu Guanghan School of Electronic and Information Engineering Beihang University School of Aerospace Tsinghua University

In order to determine an appropriate attitude of three-axis stabilized communication satellites, this paper describes a novel attitude determination method using direction of arrival （DOA） estimation of a ground signal source. It differs from optical measurement, magnetic field measurement, inertial measurement, and global positioning system （GPS） attitude determination. The proposed method is characterized by taking the ground signal source as the attitude reference and acquiring attitude information from DOA estimation. Firstly, an attitude measurement equation with DOA estimation is derived in detail. Then, the error of the measurement equation is analyzed. Finally, an attitude determination algorithm is presented using a dynamic model, the attitude measurement equation, and measurement errors. A developing low Earth orbit （LEO） satellite which tests mobile communication technology with smart antennas can be stabilized in three axes by corporately using a magnetometer, reaction wheels, and three-axis magnetorquer rods. Based on the communication satellite, simulation results demonstrate the effectiveness of the method. The method could be a backup of attitude determination to prevent a system failure on the satellite. Its precision depends on the number of snapshots and the input signal-to-noise ratio （SNR） with DOA estimation.

关键词： Attitude determination Communication satellite Direction of arrival (DOA) estimation Low Earth orbit (LEO) Smart antennas