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Experimental research on reasonable lubricant quantity for transmission gears used in high-speed train

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Science China(Technological Sciences) 2012年第12期55卷 3455-3461页

作者： LIU Ying zhang XiangJun zhang yiming MENG YongGang State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

The transmission efficiency, bulk temperature, integrate temperature, and scuffing load of test gears were investigated by a modified FZG rig. These values were measured in four different oil immersion depths with one kind of potential oil that may be used to replace the current synthetic oil in order to find the reasonable lubricant quantity that meets not only the need of transmission performance but also the need of scuffing resistance for high-speed train gears. For the purpose of evaluating the efficiency of the test gears, there were two sensors added to measure the output torque of testing gears and the compensation torque of motor. The minimum lubrication film thickness at the pitch point was gained through an EHL model. The ratio of the film thickness A was used to identify the friction status when scuffing occurred at different oil levels. The results demonstrated that no matter what kind of the immersion depth was, the minimum film thickness on the pitch point was about 0.1 ~m and the ratio of film thickness was about 1.5 when scuffing occurred. According to the relationship of contact pressure and ratio of film thickness at the pitch point, it was found that the immersion depth of pinion should not be less than one module of the gear when the contact pressure of high-speed train gear at pitch point was about 580 MPa, which was the actual pressure at start-up stage.

关键词： gears high speed train lubricant quantity FZG rig

Robust nonlinear controller design of wind turbine with doubly fed induction generator by using Hamiltonian energy approach

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控制理论与应用（英文版） 2013年第2期11卷 282-287页

作者： Bing WANG Yanping QIAN yiming zhang College of Energy and Electrical Engineering Hohai University Renewable Energy Power Generation Technology Engineering Research Center of Education Ministry Hohai University

Based on Hamiltonian energy theory, this paper proposes a robust nonlinear controller for the wind turbine with doubly fed induction generator （DFIG）, such that the closed-loop system can achieve its stability. Furthermore, in the presence of disturbances, the closed-loop system is finite-gain L2 stable by the Hamiltonian controller. The Hamiltonian energy approach provides us a physical insight and gives a new way to the controller design. The simulation results illustrate that the proposed method is effective and has its advantage.

关键词： Hamiltonian energy theory Wind turbine Doubly fed induction generator Robust control

Habitat Influence on the Molecular, Carbon and Hydrogen Isotope Compositions of Leaf Wax n-Alkanes in a Subalpine Basin, Central China

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Journal of Earth Science 2020年第4期31卷 845-852页

作者： Chaoyang Yan yiming zhang Yanzhen zhang Zhiqi zhang Xianyu Huang State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430078China Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430078China

Epidermal leaf waxes of terrestrial higher plants have been widely utilized for the reconstructions of paleoenvironment and paleoclimate in peat deposits. In this study, specimens of four plant species growing in both peatland and non-peatland habitats were retrieved to compare their molecular, carbon(δ13 C) and hydrogen(δ2 H) isotopic compositions of leaf wax n-alkanes from a closed subalpine basin in Central China. Three of the four species show quite higher total concentrations of n-alkanes in the relatively dry non-peatland setting than in the peatland. In addition, the δ2 H values of long-chain n-alkanes are generally less depleted in the peatland and are comparable among different plant species, which is interpreted as the influence of inundation condition and the possible limited supply of photosynthetic products. This study reveals different patterns of plant wax molecular and isotopic compositions between peatland and the surrounding non-peatland conditions, and confirms the paleoenvironmental potential of leaf wax ratios on the peat sequences.

关键词： habitat n-alkane compound specific carbon isotope compound specific hydrogen isotope peat deposit

An Efficient and Secure Privacy-Preserving Federated Learning Framework Based on Multiplicative Double Privacy Masking

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Computers, Materials & Continua 2024年第9期80卷 4729-4748页

作者： Cong Shen Wei zhang Tanping Zhou yiming zhang Lingling zhang College of Cryptography Engineering Engineering University of PAPXi’an710086China Key Laboratory of People’s Armed Police for Cryptology and Information Security Xi’an710086China College of Information Engineering Engineering University of PAPXi’an710086China

With the increasing awareness of privacy protection and the improvement of relevant laws,federal learning has gradually become a new choice for cross-agency and cross-device machine *** order to solve the problems of privacy leakage,high computational overhead and high traffic in some federated learning schemes,this paper proposes amultiplicative double privacymask algorithm which is convenient for homomorphic addition *** combination of homomorphic encryption and secret sharing ensures that the server cannot compromise user privacy from the private gradient uploaded by the *** the same time,the proposed TQRR(Top-Q-Random-R)gradient selection algorithm is used to filter the gradient of encryption and upload efficiently,which reduces the computing overhead of 51.78%and the traffic of 64.87%on the premise of ensuring the accuracy of themodel,whichmakes the framework of privacy protection federated learning lighter to adapt to more miniaturized federated learning terminals.

关键词： Federated learning privacy protection homomorphic encryption double mask secret sharing gradient selection

DRIFT Study on Cr2O3-SO42-/TiO2 Catalyst for Low Temperature Selective Catalytic Reduction of NO with NH3

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Chemical Research in Chinese Universities 2014年第2期30卷 279-283页

作者： zhang yiming zhang He ZHOU Liang HAN Wei College of Physics Jilin University Changchun 130012 P.R.China National Key Lab of High Power Semiconductor Lasers Changchun University of Science and Technology Changchun 130022 P.R.China

Chromium oxides supported on TiO2 showed good activity for the selective catalytic reduction of NO by *** catalytic activity of Cr2O3-SO42-/TiO2 catalyst was greatly enhanced by the addition of SO42-into TiO2 *** catalyst surface properties were characterized with NH3-TPD（temperature programmed desorption） and H2-TPR（temperature programmed reduction）.The sulphate on the catalyst surface could enhance the acidity and redox of the catalyst *** reaction mechanism on this catalyst was researched in detail by in situ diffuse reflectance Fourier transform infrared（FTIR） ***-Rideal and Langmuir-Hinshelwood mechanism existed simultaneously for selective catalytic reduction（SCR） reaction of NO over Cr2O3-SO42-/TiO2 catalyst.

关键词： Nitric oxide Selective catalytic reduction Sulfate

Continuous-discontinuous element method for three-dimensional thermal cracking of rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第11期15卷 2917-2929页

作者： Wen Nie Junlin Wang Chun Feng yiming zhang School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China Institute of Mechanics Chinese Academy of SciencesBeijing100190China

Thermal cracking of rocks can significantly affect the durability of underground structures in engineering practices such as geothermal energy extraction,storage of nuclear waste and tunnelling in freezeethaw cycle induced *** is a scenario of strong coupled thermomechanical process involving discontinuity behaviours of *** this context,a numerical model was proposed to investigate the thermal cracking of rocks,in a framework of the continuous-discontinuous element method(CDEM)for efficiently capturing the initiation and propagation of multiple cracks.A simplex integration strategy was adopted to account for the influences of temperature-dependent material *** benchmark tests were considered and the obtained results were compared with analytical solutions and numerical results from the *** results show that the fracture degree of the cases when considering temperature-dependent material parameters had 10%differences approximately compared with the cases with constant parameters.

关键词： Rock thermal cracking Continuous-discontinuous element Simplex integration Temperature dependence Numerical simulation

Quantitatively assessing the pre-grouting effect on the stability of tunnels excavated in fault zones with discontinuity layout optimization:A case study

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Frontiers of Structural and Civil Engineering 2019年第6期13卷 1393-1404页

作者： Xiao YAN Zizheng SUN Shucai LI Rentai LIU Qingsong zhang yiming zhang State Key Laboratory for Geo-mechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China Geotechnical&Structural Engineering Research Center Shandong UniversityJinan 250061China

Pre?grouting is a popular ground treatment strategy utilized to enhance the strength and stability of strata during the excavation of a tunnel through a fault *** important questions need to be answered during such an ***,how should the grouting size be determined?Second,when should excavation begin after grouting?These two questions are conventionally addressed through empirical experience and standard criteria because a reliable quantitative approach,which would be preferable,has not yet been *** address these questions,we apply a recently proposed numerical approach known as discontinuity layout optimization,an efficient node-based upper bound limit analysis method.A case study is provided utilizing a tunnel located in a stratum characterized by complicated geological conditions,including soft soil and a fault *** factor of safety is used to quantitatively assess the stability of the tunnel *** influences of the grouted zone thickness and the time-dependent material properties of the grouted zone on the stability of the tunnel section are evaluated,thereby assisting designers by quantitatively assessing the effects of pre-grouting.

关键词： pre-grouting stability analysis factor of safety discontinuity layout optimization

SKY:Efficient peer-to-peer networks based on distributed Kautz graphs

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Science in China(Series F) 2009年第4期52卷 588-601页

作者： zhang yiming LU XiCheng LI DongSheng National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Many proposed P2P networks are based on traditional interconnection topologies. Given a static topology, the maintenance mechanism for node join/departure is critical to designing an efficient P2P network. Kautz graphs have many good properties such as constant degree, low congestion and optimal diameter. Due to the complexity in topology maintenance, however, to date there have been no effective P2P networks that are proposed based on Kautz graphs with base ~ 2. To address this problem, this paper presents the ＂distributed Kautz （D-Kautz） graphs＂, which adapt Kautz graphs to the characteristics of P2P networks. Using the D-Kautz graphs we further propose SKY, the first effective P2P network based on Kautz graphs with arbitrary base. The effectiveness of SKY is demonstrated through analysis and simulations.

关键词： peer-to-peer network Kautz graph constant degree topology maintenance D-Kautz graph

Prediction of the Pore-Pressure Built-Up and Temperature of Fire-Loaded Concrete with Pix2Pix

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Computers, Materials & Continua 2024年第5期79卷 2907-2922页

作者： Xueya Wang yiming zhang Qi Liu Huanran Wang Mechanics and Materials Science Research Center Ningbo UniversityNingbo315211China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China School of Computer Science Nanjing University of Information Science and TechnologyNanjing210044China

Concrete subjected to fire loads is susceptible to explosive spalling, which can lead to the exposure of reinforcingsteel bars to the fire, substantially jeopardizing the structural safety and stability. The spalling of fire-loaded concreteis closely related to the evolution of pore pressure and temperature. Conventional analytical methods involve theresolution of complex, strongly coupled multifield equations, necessitating significant computational efforts. Torapidly and accurately obtain the distributions of pore-pressure and temperature, the Pix2Pix model is adoptedin this work, which is celebrated for its capabilities in image generation. The open-source dataset used hereinfeatures RGB images we generated using a sophisticated coupled model, while the grayscale images encapsulate the15 principal variables influencing spalling. After conducting a series of tests with different layers configurations,activation functions and loss functions, the Pix2Pix model suitable for assessing the spalling risk of fire-loadedconcrete has been meticulously designed and trained. The applicability and reliability of the Pix2Pix model inconcrete parameter prediction are verified by comparing its outcomes with those derived fromthe strong couplingTHC model. Notably, for the practical engineering applications, our findings indicate that utilizing monochromeimages as the initial target for analysis yields more dependable results. This work not only offers valuable insightsfor civil engineers specializing in concrete structures but also establishes a robust methodological approach forresearchers seeking to create similar predictive models.

关键词： Fire loaded concrete spalling risk pore pressure generative adversarial network(GAN) Pix2Pix