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Analysis and Online Diagnosis on Plugging Fault of Servo Valve in Electro-hydraulic Regulating System of Steam Turbine

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Chinese Journal of Mechanical Engineering 2009年第2期22卷 233-237页

作者： WANG Xuanyin li xiaoxiao li Fushang State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China Thermal Engineering Facility Shandong Electrical Power Institute Jinan 250002 China

Through the study on the output signals of the electro-hydraulic regulating system in the thermal power plant, a novel method for online diagnosis of the plugging fault in the servo valve is presented. With the use of the AMESIM software, the changes of the piston displacement, the oil pressure, the magnitude attenuation and the phase lag of the system under different plugging states are studied after simulation. Besides, the influences of the symmetrical and unsymmetrical plugging on the system are also compared and the characteristic table is given. The duo-neural network is put forward to achieve an online diagnosis on the plugging fault of the servo valve. The first level of network helps to make the qualitative diagnosis of the plugging position while the second level is for the quantitative diagnosis of the degree of the plugged position. The research results show that plugging at different positions exerts different influences on the performance of the system. The unsymmetrical plugging mainly affects the regulation time while the symmetrical plugging leads to great changes in the magnitude attenuation and the phase lag.

关键词： steam turbine regulating system plugging diagnosis AMESIM software

Finite p-groups whose nonnormal subgroups have orders at most p^3

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Frontiers of Mathematics in China 2014年第5期9卷 1169-1194页

作者： Qinhai ZHANG xiaoxiao li Meijuan SU Department of Mathematics Shanxi Normal University Linfen 041004 China

We classify finite p-groups all of whose nonnormal subgroups have orders at most p3, p odd prime. Together with a known result, we completely solved Problem 2279 proposed by Y. Berkovich and Z. Janko in Groups of Prim... 详细信息

关键词： Minimal non-abelian p-group nonnormal subgroup centralextension

The ONAD method for solving the SH-wave equation and simulation of the SH-wave propagation in the Earth's mantle

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Science China Earth Sciences 2013年第6期56卷 913-921页

作者： li xiaoxiao YANG DingHui TONG Ping Department of Mathematical Sciences Tsinghua University

The optimal nearly-analytic discrete(ONAD) method is a new numerical method developed in recent years for solving the wave *** with other methods,such as popularly-used finite-difference methods,the ONAD method can effectively suppress the numerical dispersion when coarse grids are *** this paper,the ONAD method is extended to solve the 2-dimensional SH-wave equation in the spherical *** investigate the accuracy and the efficiency of the ONAD method,we compare the numerical results calculated by the ONAD method and other methods for both the homogeneous model and the inhomogeneous IASP91 *** comparisons indicate that the ONAD method for solving the SH-wave equation in the spherical coordinates has the advantages of less numerical dispersion,small memory requirement for computer codes,and fast *** an application,we use the ONAD method to simulate the SH-wave propagating between the Earth's surface and the core-mantle boundary(CMB).Meanwhile,we investigate the SH-wave propagating in the mantle through analyzing the wave-field snapshots in different times and synthetic seismograms.

关键词： numerical dispersion spherical coordinates SH wave ONAD method mantle

3D large-scale SPH modeling of vehicle wading with GPU acceleration

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Science China(Physics,Mechanics & Astronomy) 2023年第10期66卷 70-91页

作者： Huashan Zhang xiaoxiao li Kewei Feng Moubin liu College of Engineering Peking UniversityBejing 100871China Joint Laboratory of Marine Hydrodynamics and Ocean Engineering Laoshan LaboratoryQingdao 266237China Nanchang Innovation Institute Peking UniversityNanchang 330008China Shenzhen TenFong Technology Co.Ltd. Shenzhen 518055China

Vehicle wading is a complex fluid-structure interaction(FSI) problem and has attracted great attention recently from the automotive industry, especially for electric vehicles. As a meshless Lagrangian particle method, smoothed particle hydrodynamics(SPH) is one of the most suitable candidates for simulations of vehicle wading due to its inherent advantages in modeling free surface flows, splash, and moving interfaces. Nevertheless, the inevitable neighbor query for the nearest adjacent particles among the support domain leads to considerable computational cost and thus limits its application in 3D large-scale simulations. In this work, a GPU-based SPH method is developed with an adaptive spatial sort technology for simulations of vehicle wading. In addition, a fast, easy-to-implement particle generator is presented for isotropic initialization of the complex vehicle geometry with optimal interpolation properties. A comparative study of vehicle wading on a puddle between the GPUbased SPH with two pieces of commercial software is used to verify the capability of the GPU-based SPH method in terms of convergence analysis, kinematic characteristics, and computing performance. Finally, different conditions of vehicle speeds, water depths, and puddle widths are tested to investigate the vehicle wading numerically. The results demonstrate that the adaptive spatial sort technology can significantly improve the computing performance of the GPU-based SPH method and meanwhile promotes the GPU-based SPH method to be a competitive tool for the study of 3D large-scale FSI problems including vehicle wading. Some helpful findings of the critical vehicle speed, water depth as well as boundary wall effect are also reported in this work.

关键词： vehicle wading fluid-structure interaction GPU-based SPH adaptive spatial sort technology

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Dynamic Reliability Evaluation and life Prediction of Transmission System of Multi-Performance Degraded Wind Turbine

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Computer Modeling in Engineering & Sciences 2023年第6期135卷 2331-2347页

作者： Rong Yuan Ruitao Chen Haiqing li WenkeYang xiaoxiao li School of Mechanical Engineering Chengdu UniversityChengdu610106China Sichuan Jiuzhou Electric Appliance Group Co. Ltd.Mianyang621000China School of Mechanical and Electrical Engineering University of Electronic Science and Technology of ChinaChengdu611731China

Wind power is a kind of important green ***,wind turbines have been widely utilized around the *** turbines are composed of many important *** these components,the failure rate of the transmission system is relatively high in wind *** is because the components are subjected to aerodynamic loads for a long *** addition,its inertial load will result in fatigue fracture,wear and other *** this situation,wind turbines have to be repaired at a higher ***,the traditional reliability methods are difficult to deal with the above challenges when performing the reliability analysis of the transmission system of wind *** solve this problem,a stress-strength interference model based on performance degradation is *** on considering the strength degradation of each component,the improved Monte Carlomethod simulation based on the Back Propagation neural network is used to obtain the curve of system reliability over ***,the Miner linear cumulative damage theory and the Carten-Dolan cumulative damage theory method are used to calculate the cumulative damage and fatigue life of the gear transmission system.

关键词： Dynamic reliability wind turbine transmission system failure correlation fatigue life

Anthraquinone derivatives supported by Ti3C2(MXene)as cathode materials for aluminum-organic batteries

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Journal of Energy Chemistry 2022年第11期31卷 174-183,I0006页

作者： Gaohong Wu Cuncai Lv Wenrong Lv xiaoxiao li Wenming Zhang Zhanyu li Hebei Key Laboratory of Optic-Electronic Information and Materials National&Local Joint Engineering Laboratory of New Energy Photoelectric DevicesCollege of Physics Science and TechnologyHebei UniversityBaoding 071002HebeiChina

Due to the advantages of aluminum in abundance in the earth’s crust and safety,how to exploit these advantages to develop high-performance rechargeable aluminum batteries to replace traditional batteries has become an urgent *** key to solving this problem is to find suitable materials as cathode for aluminum ***,we propose a strategy in which Ti_(3)C_(2)(MXene)is used as a loaded structure for the organic anthraquinone derivative Benzo[1,2-b:4,5-b’]dithiophene-4,8-dione(BDTO).This strategy enables the self-stacking of monolayer MXene into a layered structure while embedding organics into *** unique structure enables efficient and reversible intercalation/deintercalation of Al^(3+).At the same time,it exhibits excellent electrochemical performance,and its reversible capacity reaches229.8 mAh g^(-1).Moreover,it can still maintain a capacity of 134.9 mAh g^(-1)after 500 *** *** with BDTO,the rate performance of MXene@BDTO has also been greatly ***,this unique layered structure also brings better electro nic co nductivity and ionic diffusion *** also demonstrate that the battery mechanism is a reaction between three C=O and one Al^(3+) through multiple characterization methods and density functional calculations(DFT).The advantages of MXene@BDTO provide a better research basis for the study of rechargeable Aluminum-Organic batteries,and provide a good idea to explore the development of Aluminum-Organic batteries.

关键词： Aluminum-organic batteries MXene Quinone-based cathodes Carbonyl group Energy storage mechanism

3D placement of unmanned aerial vehicles and partially overlapped channel assignment for throughput maximization

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Digital Communications and Networks 2021年第2期7卷 214-222页

作者： Chengming Zou xiaoxiao li Xing liu Mengya Zhang Hubei Key Laboratory of Transportation Internet of Things Wuhan University of TechnologyWuhan430070China School of Computer Science and Technology Wuhan University of TechnologyWuhan430070China Peng Cheng Laboratory Shenzhen518055China Logistics Engineering School Wuhan University of TechnologyWuhan430070China

This paper investigates a wireless system with multi-Unmanned Aerial Vehicles(UAVs)for improving the overall *** contrast to previous studies that optimize the locations of UAVs and channel assignment separately,this paper considers the two issues jointly by exploiting Partially Overlapped Channels(POCs).The optimization problem of maximizing network throughput is formulated as a non-convex and non-linear *** order to find a practical solution,the problem is decomposed into two subproblems,which are iteratively ***,the optimal locations of UAVs are determined under a fixed channel assignment scheme by solving the mixed-integer second-order cone ***,an efficient POC allocation scheme is determined via the proposed channel assignment *** results show that the proposed approach not only significantly improves system throughput and service reliability compared with the cases in which only orthogonal channels and stationary UAVs are considered,but also achieves similar performance using the exhaustive search algorithm with lower time complexity.

关键词： Unmanned aerial vehicle Partially overlapped channel Throughput maximization Channel assignment

Interaction between GlnB and the N-terminal domain of NifA in Azospirillum brasilense

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Chinese Science Bulletin 2008年第22期53卷 3546-3552页

作者： ZHOU XiaoYu ZOU xiaoxiao li JiLun State Key Laboratory for Agrobiotechnology College of Biological Sciences China Agricultural University Beijing 100094 China

Azospirillum brasilense is a diazotroph associated with many important agricultural crops and shows potential as a biofertilizer. NifA, the transcriptional activator of nitrogen fixation (nif) genes, and GlnB, one of PII signal transduction family protein, are key proteins in the regulation of nitrogen fixation in A. brasilense. It was previously reported that the regulation of NifA activity in A. brasilense depends on GlnB. We report here that GlnB was found to interact directly with the N-terminal domain of NifA in vivo under nitrogen-free conditions and the N-terminal mutant of NifA in which the Tyr residues at position 18 and 53 were replaced by Phe (NifA-N-Y18/53F) strengthened the interaction with GlnB. Moreover, we also found that the amino acid residues 66―88 and 165―176 in N-terminus of NifA are responsible for the interaction with GlnB.

关键词： NifA GInB 蛋白质相互作用生物学研究

Multi-objective Optimization Conceptual Design of Product Structure Based on Variable Length Gene Expression

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 42-49页

作者： WEI Xiaopeng ZHAO Tingting JU Zhenhe ZHANG Shi li xiaoxiao School of Management Dalian University of Technology Dalian 116023 China Key Laboratory of Advanced Design and Intelligent Computing of Ministry of Education Dalian University Dalian 116622 China New Energy Center Shenyang Institute of Engineering Shenyang 110136 China liaoning Solar Energy R＆D Co. Ltd. Shenyang 110136 China Institute of Systems Engineering Northeastern University Shenyang 110004 China

It is a complicated problem for the bottom-to-top adaptive conceptual design of complicated products between structure and function. Reliable theories demand to be found in order to determine whether the structure accords with the requirement of design. For the requirement generally is dynamic variety as time passes, new requirements will come, and some initial requirements can no longer be used. The number of product requirements, the gene length expressing requirements, the structure of the product, and the correlation matrix are varied with individuation of customer requirements of the product. By researching on the calculation mechanisms of dynamic variety, the approaches of gene expression and variable length gene expression are proposed. According to the diversity of structure selection in conceptual design and mutual relations between structure and function as well as structure and structure, the correlation matrixes between structure and function as well as structure and structure are defined. By the approach of making the sum of the elements of correlation matrix maximum, the mathematical models of multi-object optimization for structure design are provided based on variable requirements. An improved genetic algorithm called segment genetic algorithm is proposed based on optimization preservation simple genetic algorithm. The models of multi-object optimization are calculated by the segment genetic algorithm and hybrid genetic algorithm. An example for the conceptual design of a washing machine is given to show that the proposed method is able to realize the optimization structure design fitting for variable requirements. In addition, the proposed approach can provide good Pareto optimization solutions, and the individuation customer requirements for structures of products are able to be resolved effectively.

关键词： gene expression multi-object optimization conceptual design genetic algorithm