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High-precision temperature retrieval algorithm and verification for mesospheric airglow spectrum photometer

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Science China Earth Sciences 2024年第5期67卷 1639-1651页

作者： Shuqi niu Haiyang GAO Zhaoai YAN Ke REN Leilei KOU Baichuan JIANG Lingbin BU Key Open Laboratory of Aerosol and Cloud Precipitation of China Meteorological Administration Nanjing 210044China School of Atmospheric Physics Nanjing University of Information Science and TechnologyNanjing 210044China National Space Science Center Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

Photometric technology,characterized by its compact structure and relatively high stability,finds wide application in measuring airglow *** instrumentation is anticipated to assume a pivotal role as the primary equipment for extensive network observations of middle and upper atmospheric temperatures in China,thereby providing crucial support for space environmental monitoring and atmospheric dynamic ***,susceptibility to various factors such as instrument inconsistency,variability in observation conditions,and alterations in the background atmospheric environment across different stations poses a challenge,potentially resulting in data inconsistencies in network *** response to these challenges,we propose a multiple-parameter iterative inversion(MPII)algorithm for temperature retrieval based on a mesospheric airglow spectrum photometer(MASP)developed by our research *** algorithm accurately identifies the center of the image circle,corrects image distortion,and thereby obtains an accurate synthetic spectrum reflective of actual *** encompasses five adjustable parameters:sky background light,atmospheric temperature,filter temperature,optical system focal length,and degree of synthetic spectrum *** to traditional methods,significant enhancements in the accuracy of the inverted temperature are *** validate the effectiveness of the MPII algorithm,we conducted combined active and passive remote sensing synchronous measurements using MASP in conjunction with a sodium fluorescence Doppler lidar developed by the National Space Science *** utilizing the lidar temperature as a reference,atmospheric background radiation is mitigated from the MASP data,and the temperature is inverted using the MPII *** analysis with the traditional method reveals that temperatures calculated by the MPII algorithm exhibit better consistency than those observed by the lidar.

关键词： Temperature inversion Airglow spectrum photometer Rotational spectral lines Sodium fluorescence Doppler lidar Comparative observations

Enhanced thermal conductivity and mechanical properties of 2D C_(f)/SiC composites modified by in-situ grown carbon nanotubes

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Journal of Advanced Ceramics 2024年第1期13卷 19-33页

作者： Changhui niu Qing Zhang Laifei Cheng Fang Ye Litong Zhang Min Huang Tao Yang Science and Technology on Thermostructure Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China Civil Aviation Department Zhejiang Institute of CommunicationsHangzhou 311112China Zhejiang Provincial Key Laboratory for Cutting Tools Taizhou UniversityTaizhou 318000China

In this work,the effects of carbon nanotubes(CNTs)on the microstructure evolution,thermal conductivity,and mechanical properties of C_(f)/SiC composites during chemical vapor infiltration(CVI)densification were investigated in *** with composites without CNTs,the thermal conductivity,flexural strength,flexural modulus,fracture toughness,interfacial shear strength,and proportional limit stress of specimens with CNTs of 4.94 wt%were improved by 117%,21.8%,67.4%,10.3%,36.4%,and 71.1%,*** improvement was attributed to the role of CNTs in the division of inter-layer pores,which provided abundant vapor growth sites for the ceramic matrix and promoted densification of the whole *** addition,the high thermal conductivity network formed by the overlap of CNTs and the rivet strengthening effect of CNTs were beneficial for synergistic improvement of thermal conductivity and mechanical properties of the ***,this study has practical significance for the development of thermal protection composite components with enhanced thermal conductivity and mechanical characteristics.

关键词： ceramic−matrix composites carbon nanotubes microstructure thermal conductivity mechanical properties

Optimization of Center of Gravity Position and Anti-Wave Plate Angle of Amphibious Unmanned Vehicle Based on Orthogonal Experimental Method

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2027-2041页

作者： Deyong Shang Xi Zhang Fengqi Liang Chunde Zhai Hang Yang Yanqi niu School of Mechanical Electronic&Information EngineeringChina University of Mining and Technology(Beijing)Beijing100083China Institute of Intelligent Mining&Robotics China University of Mining and Technology(Beijing)Beijing100083China

When the amphibious vehicle navigates in water,the angle of the anti-wave plate and the position of the center of gravity greatly influence the navigation *** the relevant research on reducing the navigation resistance of amphibious vehicles by adjusting the angle of the anti-wave plate,there is a lack of scientific selection of parameters and reasonable research of simulation results by using mathematical methods,and the influence of the center of gravity position on navigation characteristics is not considered at the same *** study the influence of the combinations of the angle of the anti-wave plate and the position of the center of gravity on the resistance reduction characteristics,a numerical calculation model of the amphibious unmanned vehicle was established by using the theory of computational fluid dynamics,and the experimental data verified the correctness of the numerical *** on this numerical model,the navigation characteristics of the amphibious unmanned vehicle were studied when the center of gravity was located at different positions,and the orthogonal experimental design method was used to optimize the parameters of the angle of the anti-wave plate and the position of the center of *** results show that through the parameter optimization analysis based on the orthogonal experimental method,the combination of the optimal angle of the anti-wave plate and the position of the center of gravity is *** the numerical simulation result of resistance is consistent with the predicted optimal *** with the maximum navigational resistance,the parameter optimization reduces the navigational resistance of the amphibious unmanned vehicle by 24%.

关键词： Amphibious unmanned vehicle orthogonal experimental design anti-wave plate center of gravity resistance characteristic

Synthesis of crystalline g-C_(3)N_(4) with rock/molten salts for efficient photocatalysis and piezocatalysis

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Green Energy & Environment 2024年第5期9卷 890-898页

作者： Tingting Xu Jung Hur Ping niu Shulan Wang Sangwook Lee Sang-Eun Chun Li Li Department of Chemistry College of ScienceNortheastern UniversityShenyang110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China School of Metallurgy Northeastern UniversityShenyang110819China School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea School of Industrial Technology Advances Kyungpook National UniversityDaegu41566Republic of Korea

Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics signiﬁcantly restricts its practical ***,synthesizing highly crystalline g-C_(3)N_(4) with sufﬁcient surface activities still remains ***,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed *** rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for ***,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt *** catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.

关键词： High crystallinity Carbon nitride Photocatalysis Piezocatalysis Overall water splitting

High-efficiency preparation of multifunctional conjugated electrospun graphene doped PVDF/CF yarns for energy harvesting and human movement monitoring in TENG textile

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Nano Research 2024年第5期17卷 4478-4488页

作者： Ting Yang Chengwei Wan Xiaoyu Zhang Tong Liu Li niu Jian Fang Yuqing Liu College of Textile and Clothing Engineering Soochow UniversitySuzhou 215123China

Portable power is an effective solution to realize self-powered sensors for wearable devices,promoting future sustainable ***-based triboelectric nanogenerators(M-TENGs)have emerged as a promising technology for harvesting biomechanical energy from human motion owing to their advantages,such as simple structure,lightweight design,and efficient energy ***,the poor durability,low adaptability,and un-washability of two-dimensional membrane materials have largely hindered their application in wearable *** this study,we propose a sheath-core polyvinylidene fluoride(PVDF)/graphene(G)-carbon fiber(CF)yarn fabricated via conjugate electrospinning,comprising a commercial CF core and an electrospun graphene-doped PVDF sheath,which improves the fatigue resistance of electrospun nanofiber films under prolonged friction and keeps a high degree of *** resulting electronic textile,woven with the large-scale electrospun PVDF/G-CF yarn,demonstrates a remarkable power density of 25.5 mW·m^(-2).The tight distribution of PVDF/G nanofibers on the textile surface ensures excellent softness,washability,and ***,the electrospun PVDF/G-CF textile exhibits significant potential in pressure sensing,self-powered operation,and motion detection,making it highly suitable for wearable electronics applications.

关键词： yarn-based triboelectric nanogenerator(TENG) graphene polyvinylidene fluoride(PVDF) conjugated-electrospinning multifunctional

Investigation on damage mechanism of compressor blades in turboshaft engine induced by ice impacts at various locations

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Acta Mechanica Sinica 2024年第7期40卷 181-194页

作者： Hao niu Chao Li Anhua Chen Guangfu Bin Lun Long Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment Hunan University of Science and TechnologyXiangtan 411201China AECC HAPRI Key Laboratory of Aero-engine Vibration Technology Zhuzhou 412000China

Ice causes impact damage to different positions of the compressor blade,destroys the structural integrity of the rotor structure,and then causes unbalanced failure and even causes nonlinear vibration accidents such as collision and friction,which affects the execution of helicopter *** investigate the influence of impact position on the damage form and dynamic response of blades during ice impact,a dynamic model by finite element-smooth particle fluid dynamic coupling method is *** ice impact damage experiment of the TC4 plate based on the air gun experimental platform was carried out to verify the reliability of the simulation *** damage of compressor blades impacted by ice from different positions under static and design speed of 45000 r/min is *** research results indicate that under static conditions,the damage caused by ice impact from the leading edge blade tip to the leading edge blade root first increases and then decreases,with the maximum damage occurring at the 66.7%blade height position on the leading *** the design speed,the closer the impact locations are to the leaf tip,the greater the damage is,and the plastic damage,equivalent stress,and kinetic energy loss of the ice impact are lower than the blade static *** research conclusion can provide theoretical reference and data support for the design of structural strength and protection of compressor blades in turboshaft engines.

关键词： Turboshaft engine Compressor blade Ice Impact damage simulation Dynamic response

Model for estimating the weight-loss ratio of damaged Korla fragrant pears

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 261-266页

作者： Yang Liu Yurong Tang Hong Zhang Hao niu Haipeng Lan College of Mechanical and Electrical Engineering Tarim UniversityAlaer 843300XinjiangChina College of Water Resources and Architectural Engineering Tarim UniversityAlaer 843300XinjiangChina

To predict the weight-loss ratio of Korla fragrant pears effectively,improve commodity value and study the variation laws of the weight-loss ratio of damaged fragrant pears during storage,this study predicted the weight-loss ratio of fragrant pears by utilizing the generalized regression neural network(GRNN),support vector regression(SVR),partial least squares regression(PLSR)and error back propagation neural network(BPNN).The prediction performances of GRNN,SVR,PLSR and BPNN models were compared comprehensively,and the optimal model was *** addition,the optimal prediction model was *** results show that weight-loss ratio of fragrant pears increases gradually with the extension of storage *** storage,the weight-loss ratio of fragrant pears is positively related to the degree of *** trained GRNN,SVR,PLSR and BPNN models can be used to predict the weight-loss ratio of fragrant *** BPNN model is the most accurate in predicting the weight-loss ratio of damaged fragrant pears(R^(2)=0.9929;RMSE=0.2138).It has also been proved to have good predictive effect in production practice(R^(2)=0.9377,RMSE=0.7138).The research findings can provide references to predict the delivery quality and time of delivery of Korla fragrant pears.

关键词： Korla fragrant pears weight-loss ratio damages storage time

DeepOCL:A deep neural network for Object Constraint Language generation from unrestricted nature language

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CAAI Transactions on Intelligence Technology 2024年第1期9卷 250-263页

作者： Yilong Yang Yibo Liu Tianshu Bao Weiru Wang Nan niu Yongfeng Yin School of Software Beihang UniversityBeijingChina College of Computer Science and Technology Guizhou UniversityGuiyangGuizhouChina Faculty of Information Technology Beijing University of TechnologyBeijingChina Department of Electrical Engineering and Computer Sciences University of CincinnatiCincinnatiOhioUSA

Object Constraint Language(OCL)is one kind of lightweight formal specification,which is widely used for software verification and validation in NASA and Object Management Group *** OCL provides a simple expressive syntax,it is hard for the developers to write correctly due to lacking knowledge of the mathematical foundations of the first-order logic,which is approximately half accurate at the first stage of devel-opment.A deep neural network named DeepOCL is proposed,which takes the unre-stricted natural language as inputs and automatically outputs the best-scored OCL candidates without requiring a domain conceptual model that is compulsively required in existing rule-based generation *** demonstrate the validity of our proposed approach,ablation experiments were conducted on a new sentence-aligned dataset named *** experiments show that the proposed DeepOCL can achieve state of the art for OCL statement generation,scored 74.30 on BLEU,and greatly outperformed experienced developers by 35.19%.The proposed approach is the first deep learning approach to generate the OCL expression from the natural *** can be further developed as a CASE tool for the software industry.

关键词： deep learning OCL software engineering

The Astrometric Performance of the China Space Station Telescope(CSST)Sky Survey in Extending the Gaia Celestial Reference Frame

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Research in Astronomy and Astrophysics 2024年第8期24卷 133-140页

作者： Jun Yao Jia-Cheng Liu niu Liu Zi Zhu Zhen-Wei Wang School of Astronomy and Space Science Key Laboratory of Modern Astronomy and Astrophysics(Ministry of Education)Nanjing UniversityNanjing 210023China University of Chinese Academy of Sciences Nanjing 211135China

The multi-color imaging sky survey conducted by the China Space Station Telescope(CSST)holds significant promise for advancing the development of the celestial reference *** this study,we focus on assessing the astrometric performance of the CSST celestial reference frame(CSST-CRF)in extending the Gaia Celestial Reference Frame 3(Gaia-CRF3).First,the orientation precision of the CSST reference frame is evaluated using a simulated set of extragalactic sources with CSST g magnitudes ranging from 18 to 25 *** estimated orientation uncertainty caused by random error insignificantly affects the alignment between Gaia-CRF3 and the ***,the systematic effect of incomplete CSST sky coverage on the alignment between CSST-CRF and Gaia-CRF3 is discussed by analyzing the differences between the subset of Gaia-CRF3 in the CSST observation region(Gaia-CRF3′)and Gaia-CRF3 as a *** the third International Celestial Reference Frame(ICRF3)S/X band as an intermediate reference frame,the orientation offset between Gaia-CRF3′and GaiaCRF3 is estimated to be 20μ*** offset is marginally larger than the orientation offset between Gaia-CRF3 and the ICRF3,approximately 15μ*** residual spin and glide rate of Gaia-CRF3′are derived from the proper motions,consistent with that of Gaia-CRF3 within the formal ***,we explore the role of CSST in establishing a multi-band celestial reference frame by comparing its limiting magnitude and observation accuracy with existing catalogs in the infrared and ultraviolet *** to its broad wavelength coverage and highprecision measurements,CSST is well-positioned to make significant contributions to the development of a multiband celestial reference frame.

关键词： astrometry-reference systems-surveys