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Experimental study of rotor blades vibration and noise in multistage high pressure compressor and their relevance

Chinese Journal of Aeronautics 2020年第3期33卷 870-878页

作者： Fengtong ZHAO Xiaodong JING Mingsui YANG Deyou WANG Yundong SHA Xiaochi LUAN School of Energy and Power Engineering Beihang UniversityBeijing 100191China Liaoning Province Key Laboratory of Advanced Measurement And Test Technology of Aviation Propulsion Systems Shenyang Aerospace UniversityShenyang 110136China Shenyang Engine Design and Research Institute Aero Engine(Group)Corporation of ChinaShenyang 110015China

Rotor blades fault of aeroengine compressor is mostly caused by mechanical and aerodynamic *** the excitation factor of high intensity sound wave to rotor blades should not be *** researches are conducted on a multistage high pressure *** high level vibration occurs on the first stage of rotor blades, the noise spectrum presents typical characteristic for discrete multi-tone in the *** amplitude of blade vibration displacement and the sound pressure level of characteristic frequency noise increases and decreases simultaneously and reaches the maximum value at the same *** frequency merely occur on a certain speed range and is locked in a specific range which presents no variation with the rotating *** high level vibration occurs on the first stage of rotor blades, the noise spectrum presents a sharp peak and the propagation state of the characteristic frequency is a helix structure in the *** can be confirmed that acoustic resonance occurs in the multistage *** acoustic resonance frequency and its side band frequencies are generated by modulation of a rotating noise source at the rotor speed which is the excitation source of the rotor blades vibration.

关键词： Acoustic resonance Blades vibration Characteristic frequency Multistage compressor Source identification

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Bidirectional Flow on Stairs at Different Flow Ratios 13th

Bidirectional Flow on Stairs at Different Flow Ratios

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13th Conference on Traffic and Granular Flow, TGF 2019

作者： Ye, Rui Zhang, Jun Chraibi, Mohcine Song, Weiguo State Key Laboratory of Fire Science University of Science and Technology of China Hefei230027 China Institute for Advanced Simulation Forschungszentrum Jülich Jülich52425 Germany

ISBN: (纸本)9783030559724

Bidirectional flow happens not only on horizontal planes, but also on stairs. So far, bidirectional horizontal movements have been investigated through various field studies and controlled experiments, but such movements on stairs are rarely paid attention to, especially those based on trajectories. In this paper we investigate bidirectional flow on stairs at different flow ratios ranging from 0.1 to 0.9. Preliminary results such as lane formation, crossing time and fundamental diagrams in three movement scenarios are presented, and the characteristics of the descending and ascending pedestrians are compared. Our results can be applied for the validation and calibration of simulation models on stairs. © 2020, Springer Nature Switzerland AG.

关键词： Stairs

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Unraveling the Influence of Precipitation and Temperature Variability on Anthropogenic Nutrient Inputs in a River Basin: Implications for Environmental Management

SSRN

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SSRN 2024年

作者： Zhang, Shuhui Li, Xia Ren, Ze Zhang, Cheng Fang, Le Mo, Xiaobiao Yang, Wei Liu, Xinhui Advanced Institute of Natural Sciences Beijing Normal University Zhuhai519087 China State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing100875 China Key Laboratory of Coastal Water Environmental Management and Water Ecological Restoration of Guang-dong Higher Education Institutes Beijing Normal University Zhuhai519087 China State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing210008 China Instrumentation and Service Center for Science and Technology Beijing Normal University Zhuhai519087 China Faculty of Arts and Sciences Beijing Normal University Zhuhai China

Since the Industrial Revolution, anthropogenic activities have substantially increased the input of nitrogen (N) and phosphorus (P) into river basins, complexity by interplay with climate. This study analyzed the characteristics of N and P inputs within the Dawen River Basin from 2000 to 2021 using the Net Anthropogenic Nitrogen Input (NANI) and Net Anthropogenic Phosphorus Input (NAPI) methods, and explored how those variables respond to precipitation and temperature variability. We found a generally decreasing trend in NANI over time, with an average of 17,882.34 kg N km-2 yr-1. In contrast, NAPI showed an initially increasing and then decreasing trend from 2000 to 2021, with an average value of 5,151.79 kg P km-2 yr-1. Fertilizer usage emerged as the primary source of nutrient inputs, accounting for approximately 63.42% of N and 61.88% of P inputs. Precipitation positively impacted the NANI and NAPI while temperature exerted a more influential but opposing effect. Time-lag effects were evident, as demonstrated by the stronger influences of temperature in preceding year on NANI and NAPI. Moreover, climate not only impacted the quantity of NANI and NAPI but also highly correlated to their changes, as well as the dynamics of their components. Through quantitative analyses, we unveiled key thresholds in the correlation between nutrient inputs and climate variables, with cutoffs of 14.1℃ in temperature and 820 mm in precipitation. These insights highlight the complex relationship between anthropogenic nutrient inputs and climate variability, underscoring the importance of sustainable management practices in the Dawen River Basin to mitigate negative environmental impacts. © 2024, The Authors. All rights reserved.

关键词： Nitrogen

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Design and Characterization of Low-Carbon Supersulfated Cement Prepared Using As-Received Electrolysis Manganese Dioxide Residue

SSRN

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SSRN 2023年

作者： Ma, Wenbo Bai, Tianwen Zhu, Wei Guo, Shuaicheng School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China College of Civil Engineering Xiangtan University Xiangtan411105 China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Xiangtan411105 China Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education Hunan University Changsha410082 China International Science Innovation Collaboration Base for Green & Advanced Civil Engineering Materials of Hunan Province Hunan University Changsha410082 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China

Utilizing electrolysis manganese dioxide residue (EMDR) to prepare the supersulfated cement can achieve effective waste recycling, and its application can reduce the carbon emission caused by Portland cement. This study aims to quantitatively build the correlation between the mechanical performance and cementitious matrix composition of EMDR-based supersulfated cement. The supersulfated cement containing clinker, slag and as received EMDR is designed and prepared based on the simplex centroid design method. The compressive strength, tensile strength and flexural strength of the EMDR based supersulfated cement paste were measured at 3-day, 7-day and 28-day ages. The compressive strength of the electrolysis manganese dioxide residue (EMDR) based supersulfated cement first increases and then decreases with the mass ratio between slag and EMDR. The added cement clinker can increase the compressive strength at 3-day and 7-day ages, but the 28-day age strength first decrease and then increase with the cement clinker content. Meanwhile, the flexural and tensile performances of the EMDR based supersulfated cement generally increase with the clinker content. The measured elastic modulus results indicated the added clinker could enhance the stiffness of the stiffness development. Then the strength development mechanisms of EMDR-based supersulfated cement are analyzed based on phase and microstructure characterization. It is found the clinker can accelerate the reaction rate between the slag and EMDR, and the consumption rate of the gypsum contained in EMDR. The calcium silicate hydrate (CSH) gel phase's contribution to tensile strength is more significant than that of ettringite phase. Based on the mechanism analysis, the index of [SO3]/[Al2O3] molar ratio is proposed for the matrix design of EMDR based SSC. This study can support the design and application of EMDR-based supersulfated cement. © 2023, The Authors. All rights reserved.

关键词： Aluminum oxide

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Thermomechanical degradation mechanisms of high-entropy (Yb 0.25 Er 0.25 Ho 0.25 Y 0.25 ) 2 SiO 5 environmental barrier coatings under CMAS melt infiltration

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Journal of the European Ceramic Society 2025年第15期45卷

作者： Zhijia Zhang Guo Jin Xiufang Cui Zhuo Chen Qicheng Li Shinan Hu Dechang Ma Hanchun Wang Xin Wen Haoliang Tian Haidou Wang Key Laboratory of Superlight Material and Surface Technology of Ministry of Education College of Material Science and Chemical Engineering Harbin Engineering University Harbin 150001 China Aviation Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material Beijing Beijing Institute of Aeronautical Materials Beijing 100095 China

This study examines the thermomechanical degradation mechanisms of a high-entropy (Yb 0.25 Er 0.25 Ho 0.25 Y 0.25 ) 2 SiO 5 (4REMS) environmental barrier coating under CMAS melt infiltration. The investigation considers both isothermal and thermal cycling conditions. Under isothermal exposure, the 4REMS coating exhibited excellent corrosion resistance due to the formation of a continuous apatite reaction layer that effectively inhibited melt infiltration. The synergistic dissolution of Yb 3 + , Er 3+ , Ho 3+ and Y 3+ cations in the CMAS melt promoted the formation of this dense layer. However, during cyclic corrosion testing, the emergence of microcracks compromised the structural integrity of the reaction layer, leading to an accelerated penetration rate of corrosive species. Furthermore, periodic temperature fluctuations induced dynamic instabilities in the dissolution-precipitation equilibrium, resulting in pronounced morphological alterations of apatite grains, including enhanced nucleation and coarsening.

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Berry curvature induced linear electro-optic effect in chiral topological semimetals

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Physical Review B 2022年第12期105卷 125201-125201页

作者： Zhi Li Yuewen Gao Yu Gu Shengli Zhang Toshiaki Iitaka W. M. Liu MIIT Key Laboratory of Advanced Display Materials and Devices School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China Discrete Event Simulation Research Team RIKEN Center for Computational Science 2-1 Hirosawa Wako Saitama 351-0198 Japan Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China

We studied the linear electro-optic effect of chiral topological semimetals which are characterized by high-fold chiral fermions separated in energy space. We identify that the general second-order conductivity σxyz(2)(ω) includes three sources from the shift current, injection current, and nonlinear anomalous current with frequency ω, respectively. The σxyz(2)(ω) contributed by the nonlinear anomalous current is antisymmetric under the exchange of indices x and y, and it is proportional to relaxation time and Chern number. We demonstrate that the electro-optic coefficient below 0.65 eV in chiral crystal RhSi is dominated by the nonlinear anomalous current and injection current, and it renders a relatively low half-wave voltage in the order of hundreds of volts. This work classifies how the Berry curvature modifies the linear electro-optic effect in chiral topological semimetals and opens an avenue to design the electro-optic modulator with half-wave voltage compatible with the complementary metal-oxide semiconductor circuit.

关键词： Nonlinear optics Optical conductivity Topological materials

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Low Viscosity and High Strength Room Temperature Cured Epoxy Structural Adhesive Based on Different Amine Curing Agents

SSRN

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SSRN 2022年

作者： Bi, Shuguang Xiao, Ming Huang, Liang Rong, Huaqing Jia, Liping Ran, Jianhua Quan, Heng Zhang, Liying Tang, Jiagong Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing & Finishing State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile University Wuhan430200 China State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Center for Civil Aviation Composites Donghua University Shanghai201620 China Wuhan Rongshengjimei Technology Co. LTD Wuhan430058 China

Epoxy resin has been widely used in the field of bonding owing to its low shrinkage and high adhesive performance, especially room temperature cured epoxy resin has been paid more and more attention in the field of construction engineering. However, it is still a great challenge to ensure that the epoxy adhesive with low viscosity has a high mechanical strength during rapid curing at room temperature in some construction engineering fields, such as filling repair, bonding steel reinforcement, etc. In this work, low viscosity and high strength room temperature cured epoxy structural adhesives were fabricated by using 1,4-butanediol diglycidyl ether (BDE) with difunctional groups as active diluent to reduce the viscosity of bisphenol F epoxy resin (BPF-170) and four kinds of amines, namely 2,4,6-Tris(dimethylamiomethyl)phenol (TAP), Triethylenetetramine (TETA), N-Aminoethylpiperazine (AEP) and Isophorondiamine (IPDA) as curing agents at room temperature, following by the investigation of the effects of the four different chemical structures of curing agents on the gelation time and mechanical properties of epoxy structural adhesive. Among the four kinds of epoxy structural adhesives, the BPF-170/BDE/IPDA system using alicyclic amine has the lowest viscosity of 77 mPa·s and the longest gelation time of 95.9 min. Furthermore, the BPF-170/BDE/AEP system using piperazine amine has the best mechanical properties with the shear strength, tensile strength, compressive strength and impact strength of 23 MPa, 62.5 MPa, 112.9 MPa and 2.82 kJ/m2, respectively. In addition, the four epoxy structural adhesives have great thermal stability. The initial decomposition temperatures are all above 280 ℃ and the maximum decomposition temperatures are all above 360 ℃. These four epoxy structural adhesives with low viscosity and high strength have significant application value in the fields of construction engineering, joint filling and potting repairing, etc. © 2022, The Authors. All righ

关键词： Amines

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Cross Languages One-Versus-All Speech Emotion Classifier 1

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2nd International Conference on Neural Computing for advanced Applications, NCAA 2021

作者： Liu, Xiangrui Bin, Junchi Li, Huakang Key Laboratory of Urban Land Resources Monitoring and Simulation Ministry of Natural Resources Shenzhen China School of Engineering University of British Columbia Kelowna Canada School of Artificial Intelligence and Advanced Computing Xi’an Jiaotong-Liverpool University Suzhou China Suzhou Privacy Technology Co. Ltd. Suzhou China

ISBN: (数字)9789811651885

ISBN: (纸本)9789811651878

Speech emotion recognition (SER) is a task that cannot be accomplished solely depending on linguistic models due to the presence of figures of speech. For a more accurate prediction of emotions, researchers adopted acoustic modelling. The complexity of SER can be attributed to a variety of acoustic features, the similarities among certain emotions, etc. In this paper, we proposed a framework named Cross Languages One-Versus-All Speech Emotion Classifier (CLOVASEC) that identifies speeches’ emotions for both Chinese and English. Acoustic features were preprocessed by Synthetic Minority Oversampling Technique (SMOTE) to diminish the impact of an imbalanced dataset then by Principal component analysis (PCA) to reduce the dimension. The features were fed into a classifier that was made up of eight sub-classifiers and each sub-classifier was tasked to differentiate one class from the other seven classes. The framework outperformed regular classifiers significantly on The Chinese Natural Audio-Visual Emotion Database (CHEAVD) and an English dataset from Deng. © 2021, Springer Nature Singapore Pte Ltd.

关键词： Principal component analysis

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Microstructures and phase transformation in directionally solidified TiAl-Nb alloys

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China Foundry 2020年第6期17卷 402-408页

作者： Fu-qiang Zhang Xian-fei Ding Hai Nan Ru-yue You Qiang Wang Jian-ping He Yan-qing Su Yong-feng Liang Jun-pin Lin State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Cast Titanium Alloy R&D Center Beijing Institute of Aeronautical MaterialsBeijing 100095China AECC Hunan Aviation Powerplant Research Institute Harbin 150001China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyZhuzhou 412002China

Intermetallic Ti-45Al-8Nb-(W,B,Y)(at.%)and Ti-46Al-5Nb alloys are directionally solidified at a constant growth rate of 30μm·s-1 using a Bridgman type *** quenched microstructures and lengths of different phase regions were observed and measured after various growing times of 0-30 *** show that the phase transformations in different phase regions are mainly depending on the high temperature microstructure and the supercooling degree during quenching *** isothermal holding,the primary phase grows into the liquid phase,the dendrites change from equiaxed to columnar grains,and the length of the L+βphase region,L+β+αphase region and mushy zone varies,indicating that the entire directional solidification process can be described by a static equilibrium-nonequilibrium-dynamic equilibrium evolution *** addition,the gap between the original growth interface and front interface shows that the actual crystal growth rate is not equal to the drawing velocity during directional solidification.

关键词： TiAl alloys directional solidification quenched microstructure phase transformation

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A Multi-objective optimization model for simulation-based acquisition 7

A Multi-objective optimization model for simulation-based ac...

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7th IEEE International Conference on Progress in Informatics and Computing, PIC 2020

作者： Zhang, Xue Xue, Junjie Zhou, Junhua Shi, Guoqiang Yu, Yan Nanjing University of Science and Technology School of Computer Science and Engineering Nanjing China Beijing Simulation Center Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System Engineering Beijing China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center Beijing China

ISBN: (纸本)9781728170862

Large-scale equipment presents the characteristics of technology-intensive, knowledge-intensive and complex, which brings high investment and high risk to equipment acquisition. This paper analyzes the various components of equipment acquisition to fully apply modeling and simulation technology to each stage of it. On the basis of multi-objective optimization theory, the objective function of the lowest risk and lowest cost of simulation-based acquisition (SBA) is proposed. Then establishing a multi-objective optimization model for simulation-based acquisition according to the corresponding constraints. The nondominated sorting genetic algorithm II (NSGA II) and multi-objective particle swarm optimization (MOPSO) algorithms are used to optimize the model, and the majority voting method is used for integration. The comparison of simulation examples proves that the multi-objective optimization model oriented to SBA designed in this paper can effectively realize the optimization of each objective of SBA under cost constraints. And the feasibility and efficiency of optimization solution are guaranteed. © 2020 IEEE.

关键词： Multiobjective optimization

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