Transactions of Nanjing University of Aeronautics & Astronautics
+Advanced Search
  • Current Issue
  • Online First
  • Archive
  • Most Downloaded
    Select AllDeselectExport
    Display Method:
    Flow Control with Intermittent Disturbance for the Laminar Separation Bubble on a NACA633-421 Airfoil
    SIPKADUWA MADUWA GURUGE Supun Induwara Perera, LI Linkai, WANG Shilong
    2024(S):1-12, DOI: 10.16356/j.1005-1120.2024.S.001
    [Abstract] (0) [HTML] (0) [PDF 3.44 M] (0)
    Abstract:
    This study investigates the aerodynamic performance of the NACA 633-421 airfoil and the effectiveness and feasibility of intermittent disturbance flow control methods on laminar separation bubbles （LSBs）. It is found that the average velocity and influence range of the synthetic jet actuator increase with the increasing of driving frequency and driving amplitude. LSB occurs at Re=1.0×105， and ruptures at α=6°. But with intermittent disturbance control， the stall angle of attack （AoA） increases while significantly reducing drag. Research shows that although certain disturbance cannot fully recover from LSB stall， decreasing driving amplitude partially restores wing aerodynamic performance， more effectively than increasing driving amplitude.
    3D Printing with a 5-Axis FDM Printer Using Bézier Techniques
    KHAN Abdul Basit, WANG Xiaoping
    2024(S):13-20, DOI: 10.16356/j.1005-1120.2024.S.002
    [Abstract] (0) [HTML] (0) [PDF 1.73 M] (0)
    Abstract:
    In the last decade， 3D printing， especially fused deposition modeling （FDM）， has revolutionized manufacturing with intricate designs. Traditional 3-axis FDM printers face challenges with complex geometries， but 5-axis versions offer more design freedom. However， it requires specialized strategies. This research presents a model for 5-axis FDM printers using Bézier curves with an algorithm to enhance print quality. The result shows significant accuracy improvements， especially for curve-based tasks. In addition， this study deepens the understanding of 5-axis FDM technology， setting a solid basis for further research and potentially refining manufacturing methods.
    A Multifunctional Chiral Metasurface with Asymmetric Transmission and Linear-Polarization Conversion
    AFZAL Ahmed, CAO Qunsheng, MUHAMMAD Sajjad
    2024(S):21-26, DOI: 10.16356/j.1005-1120.2024.S.003
    [Abstract] (0) [HTML] (0) [PDF 1.42 M] (0)
    Abstract:
    In this paper， a multifunctional chiral metasurface is presented to achieve asymmetric transmission （AT） and linear-polarization conversion （LPC）. The designed metasurface consists of a cross swords-like shape and two holes in the lower side of the unit cell. In the frequency band from 8.3 GHz to 10.4 GHz， AT is realized with more than 90% efficiency and the same chiral metasurface transforms linear polarized wave into its orthogonal counterpart with high efficiency. For LPC， the polarization conversion ratio （PCR） is greater than 95%. The proposed metasurface is stable against the incident angles of striking electromagnetic （EM） waves up to 60° for both operations of AT and LPC.
    Simulation of Start-Up Process of Turbofan Engine Based on Full-State Characteristics of Fan
    FANG Jun, ZHANG Tianhong
    2024(S):27-34, DOI: 10.16356/j.1005-1120.2024.S.004
    [Abstract] (0) [HTML] (0) [PDF 1.26 M] (0)
    Abstract:
    Difficulties in obtaining component characteristics in the sub-idle state of rotor constrain the simulation capabilities of ground and windmill start-up processes for turbofan engines. This paper proposes a backbone feature method based on conventional characteristics parameters to derive the full-state characteristics of fan. The application of the fan’s full-state characteristics in component-level model of turbofan engine enables zero-speed iterative simulation for ground start-up process and windmill simulation for windmill start-up process， thereby improving the simulation capability of sub-idle state during turbofan engine start-up.
    A Dual Source Power Based EV Wireless Charging System
    NAQVI Syed Zohair Raza, XIAO Lan, JIANG Menghan
    2024(S):35-42, DOI: 10.16356/j.1005-1120.2024.S.005
    [Abstract] (0) [HTML] (0) [PDF 3.23 M] (0)
    Abstract:
    Recently， there has been a huge increase in the usage of fuel resources for automobiles which is severely affecting the climate and causing global warming. The use of electric vehicle （EV） is an effective way to protect the environment and reduce travel costs. However， the EV charging system has a single charging source， and the charging rate is limited. In this paper， an EV wireless charging system based on dual source power supply has been developed. It realizes intelligent switching between 12 V photovoltaic output and 220 V AC dual source power， and has wireless transmission function. Based on the proposed power supply architecture， the micro wireless charging model is built， which enables the EV model to store power and realize static and mobile control through the wireless induction charging system.
    State Estimation Method for GNSS/INS/Visual Multi-sensor Fusion Based on Factor Graph Optimization for Unmanned System
    ZHU Zekun, YANG Zhong, XUE Bayang, ZHANG Chi, YANG Xin
    2024(S):43-51, DOI: 10.16356/j.1005-1120.2024.S.006
    [Abstract] (0) [HTML] (0) [PDF 3.56 M] (0)
    Abstract:
    With the development of unmanned driving technology， intelligent robots and drones， high-precision localization， navigation and state estimation technologies have also made great progress. Traditional global navigation satellite system / inertial navigation system（GNSS/INS） integrated navigation systems can provide high-precision navigation information continuously. However， when this system is applied to indoor or GNSS-denied environments， such as outdoor substations with strong electromagnetic interference and complex dense spaces， it is often unable to obtain high-precision GNSS positioning data. The positioning and orientation errors will diverge and accumulate rapidly， which cannot meet the high-precision localization requirements in large-scale and long-distance navigation scenarios. This paper proposes a method of high-precision state estimation with fusion of GNSS/INS/Vision using a nonlinear optimizer factor graph optimization as the basis for multi-source optimization. Through the collected experimental data and simulation results， this system shows good performance in the indoor environment and the environment with partial GNSS signal loss.
    Trigonometric Regularization and Continuation Method Based Time-Optimal Control of Hypersonic Vehicles
    LIN Yujie, HAN Yanhua
    2024(S):52-59, DOI: 10.16356/j.1005-1120.2024.S.007
    [Abstract] (0) [HTML] (0) [PDF 880.84 K] (0)
    Abstract:
    Aiming at the time-optimal control problem of hypersonic vehicles （HSV） in ascending stage， a trigonometric regularization method （TRM） is introduced based on the indirect method of optimal control. This method avoids analyzing the switching function and distinguishing between singular control and bang-bang control， where the singular control problem is more complicated. While in bang-bang control， the costate variables are unsmooth due to the control jumping， resulting in difficulty in solving the two-point boundary value problem （TPBVP） induced by the indirect method. Aiming at the easy divergence when solving the TPBVP， the continuation method is introduced. This method uses the solution of the simplified problem as the initial value of the iteration. Then through solving a series of TPBVP， it approximates to the solution of the original complex problem. The calculation results show that through the above two methods， the time-optimal control problem of HSV in ascending stage under the complex model can be solved conveniently.
    Research on High-Velocity Impact Damage Monitoring Method of CFRP Based on Guided Wave
    WANG Yang, YANG Xiaofei, QIU Lei, YUAN Shenfang
    2024(S):60-69, DOI: 10.16356/j.1005-1120.2024.S.008
    [Abstract] (0) [HTML] (0) [PDF 3.42 M] (0)
    Abstract:
    Carbon fiber-reinforced polymer （CFRP） is widely used in aerospace applications. This kind of material may face the threat of high-velocity impact in the process of dedicated service， and the relevant research mainly considers the impact resistance of the material， and lacks the high-velocity impact damage monitoring research of CFRP. To solve this problem， a real high-velocity impact damage experiment and structural health monitoring （SHM） method of CFRP plate based on piezoelectric guided wave is proposed. The results show that CFRP has obvious perforation damage and fiber breakage when high-velocity impact occurs. It is also proved that guided wave SHM technology can be effectively used in the monitoring of such damage， and the damage can be reflected by quantifying the signal changes and damage index （DI）. It provides a reference for further research on guided wave structure monitoring of high/hyper-velocity impact damage of CFRP.
    3D Ice Shape Description Method Based on BLSOM Neural Network
    ZHU Bailiu, ZUO Chenglin
    2024(S):70-80, DOI: 10.16356/j.1005-1120.2024.S.009
    [Abstract] (0) [HTML] (0) [PDF 2.92 M] (0)
    Abstract:
    When checking the ice shape calculation software， its accuracy is judged based on the proximity between the calculated ice shape and the typical test ice shape. Therefore， determining the typical test ice shape becomes the key task of the icing wind tunnel tests. In the icing wind tunnel test of the tail wing model of a large amphibious aircraft， in order to obtain accurate typical test ice shape， the Romer Absolute Scanner is used to obtain the 3D point cloud data of the ice shape on the tail wing model. Then， the batch-learning self-organizing map （BLSOM） neural network is used to obtain the 2D average ice shape along the model direction based on the 3D point cloud data of the ice shape， while its tolerance band is calculated using the probabilistic statistical method. The results show that the combination of 2D average ice shape and its tolerance band can represent the 3D characteristics of the test ice shape effectively， which can be used as the typical test ice shape for comparative analysis with the calculated ice shape.
    Wafer Defect Map Pattern Recognition Based on Improved ResNet
    YANG Yining, WEI Honglei
    2024(S):81-88, DOI: 10.16356/j.1005-1120.2024.S.010
    [Abstract] (0) [HTML] (0) [PDF 1.85 M] (0)
    Abstract:
    The defect detection of wafers is an important part of semiconductor manufacturing. The wafer defect map formed from the defects can be used to trace back the problems in the production process and make improvements in the yield of wafer manufacturing. Therefore， for the pattern recognition of wafer defects， this paper uses an improved ResNet convolutional neural network for automatic pattern recognition of seven common wafer defects. On the basis of the original ResNet， the squeeze-and-excitation （SE） attention mechanism is embedded into the network， through which the feature extraction ability of the network can be improved， key features can be found， and useless features can be suppressed. In addition， the residual structure is improved， and the depth separable convolution is added to replace the traditional convolution to reduce the computational and parametric quantities of the network. In addition， the network structure is improved and the activation function is changed. Comprehensive experiments show that the precision of the improved ResNet in this paper reaches 98.5%， while the number of parameters is greatly reduced compared with the original model， and has well results compared with the common convolutional neural network. Comprehensively， the method in this paper can be very good for pattern recognition of common wafer defect types， and has certain application value.
    Temperature and Salinity Dual-parameter Sensing Based on Forward Brillouin Scattering in 1060-XP SMF
    LIU Pengkai, ZHANG Wujun, LU Yuangang
    2024(S):89-95, DOI: 10.16356/j.1005-1120.2024.S.011
    [Abstract] (0) [HTML] (0) [PDF 1.29 M] (0)
    Abstract:
    A novel temperature and salinity discriminative sensing method based on forward Brillouin scattering （FBS） in 1060-XP single-mode fiber （SMF） is proposed. The measured frequency shifts corresponding to different radial acoustic modes in 1060-XP SMF show different sensitivities to temperature and salinity. Based on the new phenomenon that different radial acoustic modes have different frequency shift-temperature and frequency shift-salinity coefficients， we propose a novel method for simultaneously measuring temperature and salinity by measuring the frequency shift changes of two FBS scattering peaks. In a proof-of-concept experiment， the temperature and salinity measurement errors are 0.12 ℃ and 0.29%， respectively. The proposed method for simultaneously measuring temperature and salinity has the potential applications such as ocean surveying， food manufacturing and pharmaceutical engineering.
    Solution for Output Coordination Equations of Several Typical Parallel Six-Dimensional Acceleration Sensing Mechanisms
    ZHANG Xianzhu, YOU Jingjing, ZHANG Yuanwei
    2024(S):96-102, DOI: 10.16356/j.1005-1120.2024.S.012
    [Abstract] (0) [HTML] (0) [PDF 599.22 K] (0)
    Abstract:
    Aiming at the problem that it is difficult to generate the dynamic decoupling equation of the parallel six-dimensional acceleration sensing mechanism， two typical parallel six-dimensional acceleration sensing mechanisms are taken as examples. By analyzing the scale constraint relationship between the hinge points on the mass block and the hinge points on the base of the sensing mechanism， a new method for establishing the dynamic equation of the sensing mechanism is proposed. Firstly， based on the scale constraint relationship between the hinge points on the mass block and the hinge points on the base of the sensing mechanism， the expression of the branch rod length is obtained. The inherent constraint relationship between the branches is excavated and the branch coordination closed chain of the “12-6” configuration is constructed. The output coordination equation of the sensing mechanism is successfully derived. Secondly， the dynamic equations of “12-4” and “12-6” configurations are constructed by the Newton-Euler method， and the forward decoupling equations of the two configurations are solved by combining the dynamic equations and the output coordination equations. Finally， the virtual prototype experiment is carried out， and the maximum reference errors of the forward decoupling equations of the two configuration sensing mechanisms are 4.23% and 6.53%， respectively. The results show that the proposed method is effective and feasible， and meets the real-time requirements.
    Zonal Coupling Analysis Method of Seismic Response of Offshore Monopile Wind Turbine
    XU Xiaofeng, CHEN Shaolin, SUN Jie
    2024(S):103-110, DOI: 10.16356/j.1005-1120.2024.S.013
    [Abstract] (0) [HTML] (0) [PDF 1.36 M] (0)
    Abstract:
    The seismic safety of offshore wind turbines is an important issue that needs to be solved urgently. Based on a unified computing framework， this paper develops a set of seawater-seabed-wind turbine zoning coupling analysis methods. A 5 MW wind turbine and a site analysis model are established， and a seismic wave is selected to analyze the changes in the seismic response of offshore monopile wind turbines under the change of seawater depth， seabed wave velocity and seismic wave incidence angle. The analysis results show that when the seawater increases to a certain depth， the seismic response of the wind turbine increases. The shear wave velocity of the seabed affects the bending moment and displacement at the bottom of the tower. When the angle of incidence increases， the vertical displacement and the acceleration of the top of the tower increase in varying degrees.
    Improvement Mechanism of Adhesion Performance of Anti-stripping Agents and Coupling Agents on Asphalt-Aggregate Interface Based on Molecular Dynamics
    SONG Jing, XIE Jianguang, DAI Zexinyu
    2024(S):111-120, DOI: 10.16356/j.1005-1120.2024.S.014
    [Abstract] (0) [HTML] (0) [PDF 2.12 M] (0)
    Abstract:
    This study examined the mechanisms for improving the adhesion performance of the asphalt-aggregate interface with two anti-stripping agents and two coupling agents. The investigation of contact behavior between various asphalt-aggregate surfaces was conducted using molecular dynamics （MD） simulations. The interaction energy and the relative concentration distribution were employed as the parameters to analyze the enhancement mechanisms of anti-stripping agents and coupling agents on the asphalt-aggregate interface. Results indicated that the adhesion at the asphalt-aggregate interface could be strengthened by both anti-stripping agents and coupling agents. Anti-stripping agents primarily improve adhesion through the reinforcement of electrostatic attraction， while coupling agents primarily upgrade adhesion by strengthening the van der Waals. Hence， the molecular dynamics modeling and calculation techniques presented in this study can be utilized to elucidate the development mechanism of the asphalt-aggregate interface through the use of anti-stripping agents and coupling agents.
    Select AllDeselectExport
    Display Method:

NewsMore+

Articles

WeChat

Mobile website

Website Copyright © Transactions of Nanjing University of Aeronautics & Astronautics
Supported by:Beijing E-Tiller Technology Development Co., Ltd.