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Chinese Journal of Mechanical Engineering 2009年第1期22卷 36-41页

作者： LONG Jiangqi LAN Fengchong CHEN Jiqing yu Ping School of Mechanical ＆ Automotive Engineering South China University of Technology Guangzhou 510641 China

For optimal design of mechanical clinching steel-aluminum joints, the back propagation （BP） neural network is used to research the mapping relationship between joining technique parameters including sheet thickness, sheet hardness, joint bottom diameter etc., and mechanical properties of shearing and peeling in order to investigate joining technology between various material plates in the steel-aluminum hybrid structure car body. Genetic algorithm （GA） is adopted to optimize the back-propagation neural network connection weights. The training and validating samples are made by the BTM Tog-L-Loc system with different technologic parameters. The training samples＇ parameters and the corresponding joints＇ mechanical properties are supplied to the artificial neural network （ANN） for training. The validating samples＇ experimental data is used for checking up the prediction outputs. The calculation results show that GA can improve the model＇s prediction precision and generalization ability of BP neural network. The comparative analysis between the experimental data and the prediction outputs shows that ANN prediction models after training can effectively predict the mechanical properties of mechanical clinching joints and prove the feasibility and reliability of the intelligent neural networks system when used in the mechanical properties prediction of mechanical clinching joints. The prediction results can be used for a reference in the design of mechanical clinching steel-aluminum joints.

关键词： genetic algorithm BP neural network mechanical clinching joint properties prediction

SCC investigation of low alloy ultra-high strength steel 30CrMnSiNi2A in 3.5wt% NaCl solution by slow strain rate technique

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Chinese Journal of Aeronautics 2014年第5期27卷 1327-1333页

作者： Liu Jianhua Guo Qiang yu Mei Li Songmei Key Laboratory of Aerospace Materials & Performance (Ministry of Education) School of Materials Science and Engineering Beihang University

To evaluate stress corrosion cracking（SCC） mechanism of low alloy ultra-high strength steel 30CrMnSiNi2 A in environment containing NaCl, SCC behavior of the steel in 3.5wt% NaCl solution is investigated by slow strain rate technique（SSRT） with various strain rates and applied potentials, surface analysis technique, and electrochemical measurements. SCC susceptibility of the steel increases rapidly with strain rate decreasing from 1 · 10 5s 1to 5 · 10 7s 1, and becomes stable when strain rate is lower than 5 · 10 7s 1. SCC propagation of the steel in the solution at open circuit potential（OCP） needs sufficient hydrogen which is supplied at a certain strain *** surface at OCP has similar characteristics with that at cathodic polarization 1000 mVSCE, which presents characteristic fractography of hydrogen induced cracking（HIC）.All of these indicate that SCC behavior of the steel in the solution at OCP is mainly controlled by HIC rather than anodic dissolution（AD）.

关键词： Hydrogen NaCl solution Stress corrosion cracking Slow strain rate technique Ultra-high strength steel

Memristor bridge-based low pass filter for image processing

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Journal of Systems Engineering and Electronics 2019年第3期30卷 448-455页

作者： yu Yongbin YANG Nijing YANG Chenyu NYIMA Tashi School of Information and Software Engineering University of Electronic Science and Technology of China Chengdu 610054 China School of Information Science and Technology Tibet University Lhasa 850012 China

This paper highlights the memristor bridge-based lowpass filter (LPF) and improved image processing algorithms along with a novel adaptive Gaussian filter for denoising image and a new Gaussian pyramid for scale invariant feature transform (SIFT). First, a novel kind of LPF based on the memristor bridge is designed, whose cut-off frequency and other traits are demonstrated to change with different time and memristance. In light of the changeable parameter of the memristor bridge-based LPF, a new adaptive Gaussian filter and an improved SIFT algorithm are presented. Finally, experiment results show that the peak signalto- noise ratio (PSNR) of our denoising is bettered more than 2.77 dB compared to the corresponding of the traditional Gaussian filter, and our improved SIFT performances including the number of matched feature points and the percent of correct matches are higher than the traditional SIFT, which verifies feasibility and effectiveness of our algorithm.

关键词： memristor bridge low-pass filter (LPF) adaptive Gaussian filter image denoising Gaussian pyramid

Large eddy simulation of turbulent premixed piloted flame using artificial thickened flame model coupled with tabulated chemistry

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Applied Mathematics and Mechanics(English Edition) 2018年第9期39卷 1277-1294页

作者： Zhou yu Hongda ZHANG Taohong YE Minming ZHU Department of Thermal Science and Energy Engineering University of Science and Technology of China Shenyang Engine Research Institute Aero Engine (Group) Corporation of China

A sub-grid scale(SGS) combustion model, which combines the artificial thickened flame(ATF) model with the flamelet generated manifold(FGM) tabulation method, is proposed. Based on the analysis of laminar flame structures, two self-contained flame sensors are used to track the diffusion and reaction processes with different spatial scales in the flame front, respectively. The dynamic formulation for the proposed SGS combustion model is also performed. Large eddy simulations(LESs) of Bunsen flame F3 are used to evaluate the different SGS combustion models. The results show that the proposed SGS model has the ability in predicting the distributions of temperature and velocity reasonably, while the predictions for the distributions of some species need further improvement. The snapshots of instantaneous normalized progress variables reveal that the flame is more remarkably and severely wrinkled at the flame tip for flame *** satisfactory results obtained by the dynamic model indicate that it can preserve the premixed flame propagation characteristics better.

关键词： large eddy simulation(LES) artificial thickened flame model tabulation dynamic modeling flame sensor

Triboelectric nanogenerators with gold-thin-film-coated conductive textile as floating electrode for scavenging wind energy

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Nano Research 2018年第1期11卷 101-113页

作者： Bhaskar Dudem Dong Hyun Kim Jae Su yu Department of Electronic Engineering Kyung Hee University 1732 Deogyeong-daero Giheung-gu Yongin-si Gyeonggi-do 446-701Republic of Korea

We report triboelectric nanogenerators （TENGs） composed of a flexible and cost-effective gold-coated conductive textile （CT） to convert wind energy into electricity. The Au-coated CT is employed because of its high surface roughness resulting from Au nanodots distributed on microsized fibers. Thus, the Au-coated CT with nano/microarchitecture plays an important role in enhancing the effective contact area as well as the output performance of the TENG. Moreover, the surface roughness of the Au-coated CT is controlled by adjusting the Au thermal deposition time or tailoring the diameter of the Au nanodots. At an applied wind speed of 10 m.s-1, a wind-based TENG （W-TENG） with dimensions of 75 mm × 12 mm ×25 mm produces an open-circuit voltage （Voc） of - 39 V and a short-circuit current （Isc） of - 3 A by using the airflow-induced vibrations of an optimized Au-coated CT between two flat polydimethylsiloxane （PDMS） layers. To further specify the device performance, the electric output of the W-TENG is analyzed by varying several parameters such as the distance between the PDMS layer and Au-coated CT, applied wind speed, external load resistance, and surface roughness of the PDMS layers. Introducing an inverse micropyramid architecture on the PDMS layers further improves the output performance of the W-TENG, which exhibits the highest Voc （- 49 V） and Isc （- 5μA） values at an applied wind speed of 6.8 m.s-1. Additionally, the reliability of the W-TENG is also tested by measuring its output current during long-term cyclic operation. Furthermore, the rectified output signals observed by the W-TENG device are used as a direct power source to light 45 green commercial light-emitting diodes connected in series and also to charge capacitors （100 and 4.7μF）. Finally, the output performance of the W-TENG device in an actual windy situation is also investigated.

关键词： triboelectric nanogenerators Au-coated conductivetextile polydimethylsiloxanelayer wind energy

Missile autopilot design based on robust LPV control

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Journal of Systems Engineering and Electronics 2017年第3期28卷 536-545页

作者： yuanchuan Shen Jianqiao yu Guanchen Luo yuesong Mei School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China China Academy of Space Technology Beijing 100086China

This paper proposes an effective algorithm to work out the linear parameter-varying (LPV) framework autopilot for the air defense missile so as to simultaneously guarantee the closed-loop system properties globally and locally, which evidently reduces the number of unknown variables and hence increases the computational efficiency. The notion of 'robust quadratic stability' is inducted to meet the global properties, including the robust stability and robust performance, while the regional pole placement scheme together with the adoption of a model matching structure is involved to satisfy the dynamic performance, including limiting the 'fast poles'. In order to reduce the conservatism, the full block multiplier is employed to depict the properties, with all specifications generalized in integral quadratic constraint frame and finally transformed into linear matrix inequalities for tractable solutions through convex optimization. Simulation results validate the performance of the designed robust LPV autopilot and the proposed framework control method integrating with the full block multiplier approach and the regional pole placement scheme, and demonstrate the efficiency of the algorithm. An efficient algorithm for the air defense missile is proposed to satisfy the required global stability and local dynamical properties by a varying controller according to the flight conditions, and shows sufficient promise in the computational efficiency and the real-time performance of the missile-borne computer system.

关键词： linear parameter-varying (LPV) full-block multiplier integral quadratic constraint regional pole placement linear matrix inequality

Selection and characterization of eight freshwater green algae strains for synchronous water purification and lipid production

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Frontiers of Environmental Science & Engineering 2016年第3期10卷 548-558页

作者： Jingjing ZHAN Qiao ZHANG Momei QIN yu HONG Beijing Key Laboratory for Source Control Technology of Water Pollution College of Environmental Science and Engineering Beijing Forestry University Beijing 100083 China State Environmental Protection Key Laboratory of Drinking Water Source Management and Technology Shenzhen Key Laboratory of Drinking Water Source Safety Control Shenzhen Research Academy of Environmental Sciences Shenzhen 518001 China

The objective of this study is to select and characterize the candidate for synchronous water purification and lipid production from eight freshwater microalgae strains （Chlorella sp. HQ, C. emersonii, C. pyrenoidosa, C. vulgaris, Scenedesmus dimorphus, S. quadricauda, S. obiquus, Scenedesmus sp. LX1）. The strains Chlorella sp. HQ, C. pyrenoidesa, and S. obliquus showed superiority in biomass accumulation, while the top biomass producers did not correspond to the top lipid producers. S. quadricauda achieved higher lipid content （66.1%）, and Chlorella sp. HQ and S. dimorphus ranked down in sequence, with lipid content above 30%. Considering nutrient removal ability （total nitrogen （TN）： 52.97%; total phosphorus （TP）： 84.81%）, the newly isolated microalga Chlorella sp. HQ was the possible candidate for water purification coupled with lipid production. To further investigate the lipid producing and nutrient removal mechanism of candidate microalga, the ultra structural changes especially the lipid droplets under different water qualities （different TN and TP concentrations） were characterized. The results elucidate the nutrient-deficiency （TN： 3.0 mg·L^-1; TP： 0.3 mg·L^-1） condition was in favor of forming lipid bodies in Chlorella sp. HQ at the sub-cellular level, while the biomass production was inhibited due to the decrease in chloroplast number which could further suppress the nutrient removal effect. Finally, a two- phase cultivation process （a nutrient replete phase to produce biomass followed by a nutrient deplete phase to enhance lipid content） was conducted in a photo-bioreactor for Chlorella sp. HQ to serve for algae-based synchronous biodiesel production and wastewater purification.

关键词： freshwater microalgae biomass production lipid accumulation nutrient removal

FeP nanoparticles derived from metal-organic frameworks/GO as high-performance anode material for lithium ion batteries

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Science China Chemistry 2018年第9期61卷 1151-1158页

作者： Man Gao Xiaowu Liu Hai Yang Yan yu Key Laboratory of Materials for Energy Conversion Chinese Academy of Sciences(CAS) Department of Materials Science and EngineeringUniversity of Science and Technology of China

Double carbon coated Fe P composite(Fe P@NC@r GO)was in situ fabricated via the phosphorization process of the as-prepared Prussian blue@graphene oxide(PB@GO)*** Fe P nanocrystals were successfully embedded in the nitrogen-doped porous carbon *** used as the anode for lithium ion batteries(LIBs),the Fe P@NC@r GO anode shows superior lithium storage properties,delivering a high specific capacity of 830 m A h g^(-1)after 100 cycles at 100 m A g^(-1)and excellent rate capability of 359 m A h g^(-1)at 5 A g^(-1).The outstanding performance mainly ascribes to the synergistic effect of the double carbon coating and porous structure *** introduction of porous carbon and graphene coating on Fe P nanoparticles greatly enhance the electronic conductivity of the active material and well accommodates the large volume variation of Fe P during the cycling process.

关键词： FeP Prussian blue reduced graphene oxide anode lithium ion battery

A Fast Approximation Method for Partially Observable Markov Decision Processes

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Journal of Systems Science & Complexity 2018年第6期31卷 1423-1436页

作者： LIU Bingbing KANG yu JIANG Xiaofeng QIN Jiahu Department of Automation University of Science and Technology of China

This paper develops a new lower bound method for POMDPs that approximates the update of a belief by the update of its non-zero *** uses the underlying MDP to explore the optimal reachable state space from initial belief and select actions during value iterations,which significantly accelerates the convergence ***,an algorithm which collects and prunes belief points based on the upper and lower bounds is presented,and experimental results show that it outperforms some of the state-of-art point-based algorithms.

关键词： Lower bound point-based POMDP

Improved optimal steering law for SGCMG and adaptive attitude control of flexible spacecraft

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Journal of Systems Engineering and Electronics 2015年第6期26卷 1268-1276页

作者： Lu Wang yu Guo Liping Wu Qingwei Chen School of Automation Nanjing University of Science and Technology

The issue of attitude maneuver of a flexible spacecraft is investigated with single gimbaled control moment gyroscopes （SGCMGs） as an actuator. To solve the inertia uncertainty of the system, an adaptive attitude control algorithm is designed by applying a radial basis function （RBF） neural network. An improved steering law for SGCMGs is proposed to achieve the optimal out- put torque. It enables the SGCMGs not only to avoid singularity, but also to output more precise torque. In addition, global, uniform, ultimate bounded stability of the attitude control system is proved via the Lyapunov technique. Simulation results demonstrate the effectiveness of the new steering law and the algorithm of attitude maneuver of the flexible spacecraft.

关键词： flexible spacecraft adaptive steering law attitudecontrol.