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QAR Data Imputation Using Generative Adversarial Network with Self-Attention Mechanism

Big Data Mining and Analytics 2024年第1期7卷 12-28页

作者： Jingqi Zhao Chuitian Rong Xin Dang Huabo Sun School of Computer Science and Technology Tiangong UniversityTianjin 300387China institute of aviation Safety China Academy of Civil Aviation Science and TechnologyBeijing 100028China

Quick Access Recorder(QAR),an important device for storing data from various flight parameters,contains a large amount of valuable data and comprehensively records the real state of the airline ***,the recorded data have certain missing values due to factors,such as weather and equipment *** missing values seriously affect the analysis of QAR data by aeronautical engineers,such as airline flight scenario reproduction and airline flight safety status ***,imputing missing values in the QAR data,which can further guarantee the flight safety of airlines,is *** data also have multivariate,multiprocess,and temporal ***,we innovatively propose the imputation models A-AEGAN("A"denotes attention mechanism,"AE"denotes autoencoder,and"GAN"denotes generative adversarial network)and SA-AEGAN("SA"denotes self-attentive mechanism)for missing values of QAR data,which can be effectively applied to QAR ***,we apply an innovative generative adversarial network to impute missing values from QAR *** improved gated recurrent unit is then introduced as the neural unit of GAN,which can successfully capture the temporal relationships in QAR *** addition,we modify the basic structure of GAN by using an autoencoder as the generator and a recurrent neural network as the *** missing values in the QAR data are imputed by using the adversarial relationship between generator and *** introduce an attention mechanism in the autoencoder to further improve the capability of the proposed model to capture the features of QAR *** mechanisms can maintain the correlation among QAR data and improve the capability of the model to impute missing ***,we improve the proposed model by integrating a self-attention mechanism to further capture the relationship between different parameters within the QAR *** results on real datasets demonstrate that the model can rea

关键词： multivariate time series data imputation self-attention Generative Adversarial Network(GAN)

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Effects of Heat Transfer on Laminar-to-Turbulent Transition over a Compressor Blade Operating at Low Reynolds Number

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Journal of Thermal Science 2024年第5期33卷 1826-1838页

作者： LU Lehan WANG Mingyang ZHANG Yanfeng SUN Shuang HUANG Zhen WANG Maomao Department of aviation Engineering Civil Aviation University of ChinaTianjin 300300China institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China State Key Laboratory of Aerodynamics CARDCMianyang 621000China

To control the transition process in a laminar separation bubble(LSB)over an ultra-high load compressor blade at a Re of 1.5×10^(5),the effects of wall heat transfer were considered and numerically investigated by large eddy simulations(LES).Compared with the adiabatic wall condition,the local kinematic viscosity of airflow was reduced by wall cooling;thus the effects of turbulent dissipation on the growth of fluctuations were *** such,the transition occurred much earlier,and the size of LSB became *** the cooled surface,the spanwise vortices deformed much more rapidly and the size of hairpin vortex structures was ***,the rolling-up of 3D hairpin vortices and the ejection and sweeping process very close to the blade surface was ***,the aerodynamic losses of the compressor blade were reduced by 18.2%and 38.4%for the two cooled wall *** results demonstrated the feasibility of wall cooling in controlling the transition within an LSB and reducing the aerodynamic loss of an ultra-highly loaded compressor blade.

关键词： heat transfer compressor blade laminar-to-turbulent transition loss generation

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Unsteady aerodynamic noise prediction of contra-rotating open rotor using meshless method

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Chinese Journal of Aeronautics 2024年第8期37卷 144-165页

作者： Zhiliang HONG Meng SU Haitao ZHANG Zerui XU Lin DU Lingfeng CHEN College of Safety Science and Engineering Civil Aviation University of ChinaTianjin 300300China Civil aviation Administration of China Beijing 100710China Research institute of Aero-Engine Beihang UniversityBeijing 100191China

The Contra-Rotating Open Rotor(CROR)design confronts significant noise challenges despite being one of the possible options for future green *** efficiently estimate the noise emitted from a CROR,a three-dimensional unsteady prediction model based on the meshless method is *** unsteady wake flow and the aerodynamic load fluctuations on the blade are solved through the viscous vortex particle method,the blade element momentum theory and vortex lattice ***,the acoustic field is obtained through the Farassat’s formulation *** of this method is conducted on a CROR,and a mesh-based method,e.g.,Nonlinear Harmonic(NLH)method,is also employed for *** is found that the presented method is three times faster than NLH method while maintaining a comparable precision.A thorough parametric analysis is also carried out to illustrate the effects of rotational speed,rotor-rotor spacing and rear rotor diameter on the noise *** rotor speed is found to be the most influencing factor,and by optimizing the speed difference between the front and rear rotors,a notable noise reduction can be *** current findings not only contribute to a deeper comprehension of the CROR’s aeroacoustic properties but also offer an effective tool for engineering applications.

关键词： Contra-Rotating Open Rotor(CROR) Aerodynamic noise Blade element momentum theory Viscosity vortex particle method Farassat’s formulation 1A

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Repair tolerance assessment for aircraft composite structures using Bayesian updating

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Chinese Journal of Aeronautics 2024年第6期37卷 360-391页

作者： Xin LI Hongfu ZUO Bin YANG School of Automotive and Rail Transit Nanjing Institute of TechnologyNanjing 211167China Civil aviation Key Laboratory of Aircraft Health Monitoring and Intelligent Maintenance College of Civil AviationNanjing University of Aeronautics and AstronauticsNanjing 211106China

Detection and repair of composite damage is crucial to ensure the safety and reliability of aircraft structures.A novel approach to quantitatively evaluate the repair tolerance of composite structures in civil aircraft based on Bayesian updating is *** method incorporates historical damage inspection data to determine the prior distribution of damage size,which is then updated with newly collected damage size data using Bayesian *** Carlo simulation is employed to investigate the probability of failure and estimate maintenance costs,considering various factors such as the frequency and timing of damage events,damage detection,structural strength,gust loads,and maintenance expenses throughout the lifecycle of composite *** and economic factors are considered to establish a lower threshold for repairs and an upper threshold for maintenance based on the occurrence of accidental impact *** of the effectiveness and feasibility of a quantitative assessment method for repair tolerance is conducted using damage statistics data from civil aircraft routes utilizing the structural skin panels of composite outer *** results demonstrate that the method proposed in conjunction with extensive simulations and full utilization of field damage inspection data can effectively simulate unexpected impact damage situations that may occur during civil aircraft service and evaluate the reliability and economic feasibility of the repair of *** research findings hold significant theoretical and practical value for the preparation of documents for continued airworthiness of composite structures,including structural repair manuals and maintenance programs.

关键词： Composite structures Repair tolerance Maintenance Bayesian updating Probability of failure

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Numerical study on influence of protrusion heights on Reynolds stress and viscous stress variations in turbulent vortical structures

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Chinese Journal of Aeronautics 2024年第9期37卷 59-71页

作者： Zhiping LI Long HE Jingsai ZHOU Yueren ZUO Yao YIN Peng ZHANG Bo MENG Research institute of Aero-Engine Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBejing 100191China institute of Acoustics Chinese Academy of SciencesBeijing 100190China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China AECC Hunan aviation Powerplant Research institute Zhuzhou 412002China

Analysing the infuence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet ***,the Large Eddy Simulation(LES)is used to investigate the vortex structure over the rib-let surface with different protrusion ***,the variations of Reynolds stress and viscous shear stress in a turbulent channel are *** a result,the drag reduction rate increases from 3.4%when the riblets are completely submerged in the turbulent boundary layer to 7.9%when the protrusion height is *** analysis shows that the protrusion height affects the streamwise vortices and the normal diffusivity of spanwise and normal vortices,thus driving the variation of Reynolds *** with the smooth surface,the vorticity strength and the number of streamwise vortices are weakened near the wall but increase in the logarithmic layer with increased protrusion ***,the normal diffusivity of spanwise vorticity decreases with the increase of protrusion height,and the normal diffusivity of normal vorticity is the smallest when the protrusion height is ***,the protrusion height affects the velocity gradient of the riblet tip and riblet valley,thus driving the variation of viscous shear *** the increase of protrusion height,the velocity gradient of the riblet tip increases dramatically but decreases in the riblet valley.

关键词： Riblet Dragreduction Protrusion height Vortical structure Vortexdiffusivity Reynolds stress Viscous stress

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Adaptive detection of range-spread targets in homogeneous and partially homogeneous clutter plus subspace interference

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Journal of Systems Engineering and Electronics 2024年第1期35卷 43-54页

作者： JIAN Tao HE Jia WANG Bencai LIU Yu XU Congan XIE Zikeng Research institute of Information Fusion Naval Aviation UniversityYantai 264001China Air Force Early Warning Academy Wuhan 430019China

Adaptive detection of range-spread targets is considered in the presence of subspace interference plus Gaussian clutter with unknown covariance *** target signal and interference are supposed to lie in two linearly independent subspaces with deterministic but unknown *** on the two-step criteria,two adaptive detectors based on Gradient tests are proposed,in homogeneous and partially homogeneous clutter plus subspace interference,*** of the proposed detectors exhibit theoretically constant false alarm rate property against unknown clutter covariance matrix as well as the power *** results show that,the proposed detectors have better performance than their existing counterparts,especially for mismatches in the signal steering vectors.

关键词： adaptive detection subspace interference constant false alarm rate Gradient test partially homogeneous environment

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Improvement of Film Cooling Design for Turbine Vane Leading Edge Considering Combustor Outflow

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Journal of Thermal Science 2024年第1期33卷 311-327页

作者： WANG Xinyu LIU Cunliang FU Zhongyi LI Yang ZHU Huiren School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China AECC Hunan aviation Powerplant Research institute Zhuzhou 412002China

As the interaction between the combustor and the turbine in the aero-engine continues to increase,the film cooling design considering the combustor swirling outflow has become the research *** swirling inflow and high-temperature gas first affect the vane leading edge(LE).However,no practical improved solution for the LE cooling design has been proposed considering the combustor swirling *** this paper,the improved scheme of showerhead cooling is carried out around the two ways of adopting the laid-back-fan-shaped hole and reducing the coolant outflow *** film cooling effectiveness(η) and the coolant flow state are obtained by PSP(pressure-sensitive-paint) and numerical simulation methods,*** research results show that the swirling inflow increases the film distribution inhomogeneity by imposing the radial pressure gradient on the vane to make the film excessively gather in some *** showerhead film cooling adopts the laid-back-fan-shaped hole to reduce the momentum when the coolant flows *** this cooling scheme improves the film attachment and increases the surface-averaged film cooling effectiveness(η_(sur)) by as much as15.4%,the film distribution inhomogeneity *** reducing the coolant outlet angle,the wall-tangential velocity of the coolant increases,and the wall-normal velocity *** the swirl intake condition,both ηand the film distribution uniformity are significantly increased,and the growth of η_(sur) is up to 16.5%.This paper investigates two improved schemes to improve the showerhead cooling under the swirl intake condition to provide a reference for the vane cooling design.

关键词： turbine vane showerhead cooling swirling inflow laid-back-fan-shaped hole film hole inclination

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Twin-SSB signal reception without optical SSB filters based on self-coherent detection

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Optoelectronics Letters 2024年第10期20卷 584-591页

作者： ZHANG Xiaoling Key Laboratory of aviation Electronic Information Systems Southwest China Institute of Electronic Technology

Dater center interconnection has stimulated the development of short-reach optical communication transmission. To increase the capacity of the single sideband(SSB) system with direct-detection(DD), the twin-SSB system can double the system capacity without an extra optical modulator. Recently, the Stokes vector receiver(SVR) bridges the coherent detection and DD. A carrier can be sent along with the signal so that the SVR can utilize the reference carrier to conduct self-coherent detection and realize a linear complex optical detection, which is similar to the coherent receiver. In this paper, we propose a twin-SSB reception without optical SSB filters based on self-coherent detection. The proposed scheme greatly reduces the implementation complexity and has higher spectral efficiency(SE) compared with the traditional twin-SSB signal detection where two narrow-band optical filters and guard band are used for SSB signal extracting and inter crosstalk suppression. Meanwhile, the proposed twin-SSB signal detection with self-coherent detection also helps to relax the receiver digital signal processing(DSP), since the self-coherent detection reduces the inter crosstalk between the twin-SSB. The twin-SSB reception with self-coherent detection scheme makes it suitable for future high-speed short and medium-reach applications, such as the data center interconnect and metro area network.

关键词： A

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A GMDA clustering algorithm based on evidential reasoning architecture

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Chinese Journal of Aeronautics 2024年第1期37卷 300-311页

作者： Haibin WANG Xin GUAN Xiao YI Shuangming LI Guidong SUN Naval aviation University Yantai 264001China Unit 92941 of PLA Huludao 125001China institute of Systems Engineering Beijing 100082China

The traditional clustering algorithm is difficult to deal with the identification and division of uncertain objects distributed in the overlapping region,and aimed at solving this problem,the Evidential Clustering based on General Mixture Decomposition Algorithm(GMDA-EC)is ***,the belief classification of target cluster is carried out,and the sample category of target distribution overlapping region is ***,on the basis of General Mixture Decomposition Algorithm(GMDA)clustering,the fusion model of evidence credibility and evidence relative entropy is constructed to generate the basic probability assignment of the target and achieve the belief division of the ***,the performance of the algorithm is verified by the synthetic dataset and the measured *** experimental results show that the algorithm can reflect the uncertainty of target clustering results more comprehensively than the traditional probabilistic partition clustering algorithm.

关键词： Evidential clustering Credal partition Evidential reasoning Mixed decomposition Gaussian mixture model

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Catalytic upgrading biomass-derived ethanol and acetic acid into C4 chemicals

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Science China Chemistry 2024年第11期67卷 3588-3613页

作者： Tingting Yan Mengting Zhang Runzhi Yuan Weili Dai College of Science Civil Aviation University of China School of Materials Science and Engineering & National institute for Advanced Materials Nankai University

Synthesis of value-added chemicals from biomass is an essential strategy to mitigate the global dependency on fossil resources and achieve the aim of carbon neutrality. Thereinto, ethanol and acetic acid are crucial biomass-derived platform ***, catalytic upgrading ethanol and acetic acid into C4 energy-intensive fuels and chemicals via the elongation of carbon backbone has received widespread attention. The primary focus of this review is to systematically describe the recent breakthrough in the conversion of ethanol or acetic acid to C4 chemicals including 1,3-butadiene, n-butenes, isobutene or *** attentions will be given to heterogeneous catalyst design strategies, reaction parameters on the catalytic performance along with the relevant mechanism investigations, as well as their future challenges and opportunities. The present review will provide the detailed insights into the synthesis of C4 chemicals from biomass-derived ethanol and acetic acid and shed a light on the development of highly efficient catalysts.

关键词： ethanol acetic acid C4 chemicals catalytic upgrading aldol condensation

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