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j.urnal of Modern Power Systems and Clean Energy 2019年第2期7卷 350-356页

作者： Hongshan ZHAO Yufeng GAO Huihai LIU lang LI School of Electrical and Electronic Engineering North China Electric Power University

In order to accurately identify a bearing fault on a wind turbine, a novel fault diagnosis method based on stochastic subspace identification(SSI) and multi-kernel support vector machine(MSVM) is proposed. Firstly, the collected vibration signal of the wind turbine bearing is processed by the SSI method to extract fault feature vectors. Then, the MSVM is constructed based on Gauss kernel support vector machine(SVM) and polynomial kernel SVM. Finally, fault feature vectors which indicate the condition of the wind turbine bearing are inputted to the MSVM for fault pattern recognition. The results indicate that the SSI-MSVM method is effective in fault diagnosis for a wind turbine bearing and can successfully identify fault types of bearing and achieve higher diagnostic accuracy than that of K-means clustering, fuzzy means clustering and traditional SVM.

关键词： Wind turbine Bearing Fault diagnosis Stochastic subspace identification(SSI) Multi-kernel support vector machine(MSVM)

Undesorbable residual gas in coal seams and its influence on gas drainage

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International j.urnal of Mining Science and Technology 2017年第5期27卷 763-769页

作者： Wang Gongda Ren Ting Zhang lang Shu Longyong Mine Safety Technology Branch China Coal Research Institute School of Civil Mining and Environmental EngineeringUniversity of Wollongong

The definition of ‘‘residual gas" can be found in different scenarios, such as the ‘‘fast" and ‘‘slow" desorption methods of measuring gas content and the sorption hysteresis test and gas management of coal mines, however, its meaning varies a lot in different contexts. The main aim of this paper is to discuss the existence of truly undesorbable residual gas in coal seam conditions and its impacts on sorption model and gas drainage efficiency. We believe the undesorbable residual gas does exist due to the observation of the extended slow desorption test and the sorption hysteresis test. The origin of undesorbable residual gas may be because of the inaccessible(closed or semi-closed) pores. Some gas molecules produced during coalification are stored in these inaccessible pores, since the coal is relatively intact in the coal seam condition, these gas molecules cannot escape during natural desorption and then create the undesorbable residual gas. Based on the existing adsorption models, we propose the improved desorption versions by taking into consideration the role of residual gas. By numerically simulating a gas drainage case, the gas contents after different drainage times are studied to understand the influence of residual gas content on gas drainage. The results indicate that the influence starts to be obvious even when the total gas content is at a high level, and the impact becomes more and more apparent with increasing drainage time. Our study shows that the existence of residual gas will impede the gas drainage and the total amount of recoverable coal seam methane may be less than expected.

关键词： Residual gas Inaccessible pores Desorption model Gas drainage

A Versatile Flow-Profile Engineering Method in the Stokes Flow Regime for Complex-Shaped Flows

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Engineering 2021年第5期7卷 655-662页

作者： Zhenyu Yang lang Nan Ho Cheung Shum Department of Mechanical Engineering The University of Hong KongHong Kong 999077China

Flow profiles are frequently engineered in microfluidic channels for enhanced mixing,reaction control,and material ***,flow profiles are engineered by inducing inertial secondary flow to redistribute the streams,which can hardly be reproduced in microfluidic environments with negligible inertial *** employed symmetric channel structures also limit the variety of achievable flow ***,each of the flow profiles specifically corresponds to a strictly defined flow condition and cannot be generalized to other flow *** address these issues,we present a systematic method to engineer the flow profile using inertialess secondary *** flow is manipulated in the Stokes regime by deploying a cascaded series of microsteps with various morphologies inside a microchannel to shape the flow *** tuning the shapes of the microsteps,arbitrary outflow profiles can be customized.A numerical profile-transformation program is developed for rapid prediction of the output profiles of arbitrary sequences of predefined *** proposed method allows the engineering of stable flow profiles,including asymmetric ones,over a wide range of flow conditions for complex microfluidic environmental prediction and design.

关键词： Microfluidics Flow profile Stokes flow Hydrodynamic focusing Flow shaping

Re-scaling and adaptive stochastic resonance as a tool for weak GNSS signal acquisition

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j.urnal of Systems Engineering and Electronics 2016年第2期27卷 290-296页

作者： Rongling lang Xinyue Li Fei Gao Liang Yang School of Electronics and Information Engineering Beihang UniversityBeijing 100191China China United Network Communications Company Limited Tianjin 300052China

Weak global navigation satellite system（GNSS） signal acquisition has been a limitation for high sensitivity GPS receivers. This paper modifies the traditional acquisition algorithms and proposes a new weak GNSS signal acquisition method using re-scaling and adaptive stochastic resonance（SR）. The adoption of classical SR is limited to low-frequency and periodic signals. Given that GNSS signal frequency is high and that the periodic feature of the GNSS signal is affected by the Doppler frequency shift, classical SR methods cannot be directly used to acquire GNSS signals. Therefore, the re-scaling technique is used in our study to expand its usage to high-frequency signals and adaptive control technique is used to gradually determine the Doppler shift effect in GNSS signal buried in strong noises. The effectiveness of our proposed method was verified by the simulations on GPS L1 signals. The simulation results indicate that the new algorithm based on SR can reach-181 d BW sensitivity with a very short data length of 1 ms.

关键词： weak signal detection global navigation satellite system(GNSS) signal acquisition stochastic resonance

Nonlinear Vibrations and Stability of an Axially Moving Plate Immersed in Fluid

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Acta Mechanica Solida Sinica 2019年第6期32卷 737-753页

作者： Hongying Li Tianyi lang Yongj.n Liu j.an Li Institute of Applied Mechanics College of ScienceNortheastern UniversityShenyang 110819Chinch

In this paper,the nonlinear forced vibrations and stability of an axially moving large deflection plate immersed in fluid are *** on von Karman's large deflec・tion plate theory and taking into consideration the influence of fluid-strueture interaction,axial moving and axial tension,nonlinear dynamic equations are obtained by applying D'Alembert's *** dynamic equations are further discretized into ordinary differential equations via the Galerkin *** frequency-response curves of system are obtained and *** numerical method is used to analyze the bifurcation behaviors of immersed *** show that as the parameters vary,the system displays periodic,multi-periodic,quasi-periodic and even chaotic *** the analysis on global dynamic characteristics of fluid-strueture interaction system,rich and varied nonlinear dynamic characteristics are obtained,and various ways that lead to chaotic motion of the system are further revealed.

关键词： Axially moving plate Fluid-strueture interaction Nonlinear vibrations Bifurcations

Corporate Effects of Temperature and Strain Range on the Low Cycle Fatigue Life of a Single-Crystal Superalloy DD10

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 152-158页

作者： Zhi-Dong Fan Dong Wang lang-Hong Lou Institute of Metal Research Chinese Academy of Sciences

Low cycle fatigue behavior of a nickel-based single-crystal superalloy DD10 was investigated at 760 and 980 ℃ under different strain ranges. Results show that the fatigue life （Nf） of DD10 alloy exhibits different temperature dependence under various strain ranges. Under low strain range, the alloy exhibits a longer Nf at 760 ℃ than that at 980 ℃. However, under high strain range, a reverse result is obtained. This difference can be attributed to the change of dominant damage modes under various test conditions, which is manifested in different modes of crack initiation （crack nucleation and its early propagation）. At 760 ℃, the crack initiates at pores in subsurface due to local stress concentration. This process is mainly controlled by plastic amplitude and plastic property, but not affected by oxygen-induced damage before the crack propagates to the surface. At 980 ℃, the crack initiates at surface instead of pores due to the more homogeneous plastic deformation and the disharmony between the external oxidation layer and the bulk material when the strain amplitude is high. At that temperature, the process is mainly controlled by oxidation damage and strain amplitude simultaneously. Therefore, under high strain range, the crack initiation is much easier at 760 ℃ due to plastic deformation and the poor plasticity, while under low strain range obvious oxidation damage at 980℃ may accelerate the crack initiation.

关键词： Low cycle fatigue Single-crystal superalloy Temperature Strain Crack initiation

Recent advances of nanoporous metal-based catalyst: synthesis, application and perspectives

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j.urnal of Iron and Steel Research International 2019年第8期26卷 779-795页

作者： Rui-qi Yao Xing-you lang Qing j.ang Key Laboratory of Automobile Materials (Ministry of Education) School of Materials Science and Engineering Jilin University Changchun 130022 Jilin China

Nanoporous metal-based catalysts with the specific bicontinuous interconnected ligaments/pores network exhibit highly active performances in application for energy conversion, which represent a broader trend in the design of catalyst materials. These promising nanomaterials commendably provide highly conductive porous morphologies with reduced contact resistances, large electrochemical surface areas with enhanced catalytic efficiency, and controllable synthesis for regulating the performances. Thus, we highlight recent designs of nanoporous metals, alloys, transition metal compounds and hierarchical structures mainly employed in catalysis process. We discuss applied strategies to utilize characteristics of nanoporous metals in the energetic field of catalytic reactions. Moreover, development and evolution of novel controllable synthesis methods are applied in preparation of nanoporous non-noble metals and transition metal compounds. Finally, we present some outlooks and perspectives on the nanoporous metal catalyst and suggest ways for achieving alternative materials in catalysis applications.

关键词： Nanoporous metal Electrochemical catalyst Hierarchical structure Metal-based compound Structure-activity correlation

Mechanics analysis of axisymmetric thin-walled part in warm sheet hydroforming

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Chinese j.urnal of Aeronautics 2015年第5期28卷 1546-1554页

作者： Yang Xiying lang Lihui Liu Kangning Liu Baosheng School of Mechanical Engineering and Automation Beihang University Beij.ng Aviation Manufacturing Engineering Institute

To obtain the influence of fluid pressure and temperature on warm hydroforming of 5A06-O aluminum alloy sheet, the unified mechanics equilibrium equations, which take through- thickness normal stress and friction into account, were established in spherical coordinate system. The distribution of through-thickness normal stress in the thickness direction was determined. The relation between through-thickness normal stress and fluid pressure was also analyzed in different regions of cylindrical cup. Based on the method of subtracting one increasing function from another, the constitutive equation of 5A06-O applied to warm hydroforming was established and in a good agreement with uniaxial tensile data. Based on whether the thickness variation was taken into account, two mechanic models were established to do the comparative study. The results for the studied case show that the calculated stress values are pretty close according to the two models and consistent with results of finite element analysis; the thickness distribution in flange computed by the second model conforms to the experimental data. Finally, the influences of fluid pressure on the flange thickness and radial stress were analyzed.

关键词： 5A06-O aluminum alloy:Constitutive equations:Fluid pressure:Through-thickness normalstress Warm sheet hydroforming

Dynamic Analysis of Incentive Policy Impacts on Recycling of Retired Batteries for Electric Vehicles

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j.urnal of Systems Science and Information 2024年第4期12卷 491-514页

作者： Cuixia WANG lang WEI School of Information Management Jiangxi University of Finance and EconomicsNanchang 330032China School of Economics and Management Hunan College of InformationChangsha 410200China

Electric Vehicles(EVs),as a low-carbon means of transportation,have promptly become popular worldwide in the past *** the lifespan of batteries is limited,massive of Electric Vehicle Batteries(EVBs)are being retired,resulting in a rapid increase in the demand for the recycling of retired EVBs in recent ***,due to high recycling costs and immature recycling technologies,EV manufacturers are facing significant challenges in recycling retired ***,as the country with the largest number of EV users in the world,is exploring effective incentive policies for the recycling of retired *** this context,we developed a system dynamics model to analyze the impact of incentive polices such as,recycling subsidies,technological progress,and carbon trading on the retired EVBs *** show that:1)recycling subsidies can improve the recycling ratios quickly in the short term,and dynamic subsidies are more efficient than static subsidies;2)the policy of technological advancement can reduce the recovery and cascade utilization cost,thus having a positive impact on battery recycling,but the policy effect has a time-delay;3)the carbon trading policy is unable to promote efficient recycling due to the current low carbon prices;4)dynamic subsidy and technological advancement policies complement each other,therefore,the combination of these two policies is the best way to promote the recycling of retired EVBs and reduce carbon *** is hoped that this study will contribute to the ongoing debate on policies for the industrialization of retired EVBs recycling.

关键词： electric vehicles retired battery recycling policy impact system dynamics

A corrosion-reconstructed and stabilized economical Fe-based catalyst for oxygen evolution

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Nano Research 2023年第2期16卷 2224-2229页

作者： Zhiquan lang Guang-Ling Song Pengpeng Wu Daj.ang Zheng Center for Marine Materials Corrosion and Protection Xiamen UniversityXiamen 361005China Department of Ocean Science and Engineering Southern University of Science and TechnologyShenzhen 518055China State Key Laboratory of Physical Chemistry of Solid Surfaces Xiamen UniversityXiamen 361005China The University of Queensland St.LuciaQLD 4072Australia

The anode activity can to a great degree limit the cathodic hydrogen evolution efficiency in an electrolyte ***,cost-efficient electrocatalysts with good water oxidation performance and stability are highly desired in widespread implementation of the hydrogen production from water *** paper proposes a facile corrosion-reconstruction strategy to transform Fe surface into a Fe-Co hydroxide layer to improve the oxygen evolution *** as-prepared catalyst was measured to have an over-potentential as low as 320 mV at 100 mA·cm^(−2),and its stability even exceeded 600 *** and Raman spectroscopy analyses indicated that the catalyst experienced chemical changes from hydroxides to oxyhydroxides and Co^(2+)to Co^(3+)during oxygen evolution reaction(OER).The corrosion-reconstruction is not only an economical method to synthesize a highly efficient,stable and durable Fe-based catalysts,it also converses the detrimental corrosion into a beneficial catalyst fabrication process.

关键词： oxygen evolution reaction electrocatalyst corrosion stability