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- 저자 : Yuanfang Wang (검색결과 5 건)
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A New Stability Condition for Uncertain Fuzzy Hopfield Neural Networks with Time-varying Delays
Jing Wang,Xia Liu,Jianjun Bai,Yuanfang Chen 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5
In this paper, the global asymptotic stability of uncertain fuzzy Hopfield neural networks(UFHNNs) withtime-varying delays is investigated. Firstly, a new fuzzy Lyapunov function comprising a special line-integral functionof fuzzy vector is proposed. Then by using theWirtinger-based integral inequality to determine the upper boundof the derivative term of the Lyapunov function more accurately, a new stability criterion with less conservatism isderived in the form of linear matrix inequality(LMI). At last, an examples is given to show the effectiveness andsuperiority of our result.
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Bingge Zhao,Yuanfang Wang,Kai Ding,Guanzhi Wu,Tao Wei,Hua Pan,Yulai Gao 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2
Medium Mn steels, one of the most promising 3rd generation advanced high strength steels (AHSS), achieve an encouraging trade-off between the outstanding mechanical property and the production cost. As a typical medium Mn steel, 7Mn steels have superior mechanical property but their poor cross-tension property becomes the Achilles’ heel, hindering the application in the automotive industry. The current study focuses on the cross-tension property of the resistance spot weld of 7Mn steel. Generally, martensite is produced in the nugget during the resistance spot welding (RSW). However, the microstructure in the weld nugget can be correspondingly tuned by directly optimizing the welding parameters. With post-weld pulses, in situ tempering occurs, which can decrease the segregation of Mn existing along martensite lath boundaries and facilitate the microstructure transition from martensite to tempered martensite. The tuning on the nugget microstructure facilitates the increase of cross-tension strength (CTS) from 1.5 to 3.7 kN. Although both cases fail in an interfacial fracture mode, a partial ductile fracture is demonstrated in the specimen with post-weld treatment, which is attributed to the occurrence of low-carbon α phase and second phase particles. This study elucidates that the decrease of segregation and the microstructure transition in the nugget are the dominant factor determining the CTS. It is therefore demonstrated that the reduction of Mn segregation and the formation of tempered martensite can increase the weldability of RSW joints of the medium Mn steels.
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Bingge Zhao,Yuanfang Wang,Kai Ding,Guanzhi Wu,Tao Wei,Hua Pan,Yulai Gao 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.4
Among the 3rd generation advanced high strength steels, medium Mn steels receive extensive attention sed in modern automotive industry attributing to their encouraging mechanical performance and lower production cost. Unfortunately, the poor cross-tension property of 7Mn steel, one of the typical medium Mn steels, remains a key challenge to hinder its application in automotive industry. In this study, multiple post-weld heat treatment (MPWHT) consisting of cyclic heat treatment and intercritical annealing was employed to improve the cross-tension property of the resistance spot weld of 7Mn steel. With this method, the diffusion of Mn was significantly enhanced, eliminating their severe segregation along the martensite lath boundaries. Additionally, MPWHT facilitated the structure tailoring: the cyclic heat treatment between room and austenization temperature produced the so-called martensitic transformation induced grain refinement and austenite stability while the intercritical annealing triggered austenite reversion transformation, leading to a mixed structure of refined ferrite and austenite across the weld. With the optimization in composition homogeneity and structure tuning, the cross-tension strength (CTS) of a resistance spot welded 7Mn steel stood at 12.7 kN, which is so far the ultrahigh level to our best knowledge. Moreover, this effort brought on button failure mode, suggesting the dominant ductility deformation during the cross-tension test. In a word, the current study achieved an exceptional trade-off between the outstanding CTS and ductility of the resistance spot weld of 7Mn steel by the MPWHT consisting of cyclic heat treatment and intercritical annealing.
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Bacterial Fruit Rot of Apricot Caused by Burkholderia cepacia in China
Yuan Fang,Bin Li,Fang Wang,Baoping Liu,Zhiyi Wu,Ting Su,Wen Qiu,Guanlin Xie 한국식물병리학회 2009 Plant Pathology Journal Vol.25 No.4
An unreported disease of apricot was observed in orchards in Zhejiang province, China. Symptoms started as water soaked lesions on the fruit surface. Later, water-soaked areas developed and spread to the entire fruit, resulting in soft rot of the whole fruit. The causal organism isolated from symptomatic fruits was identified as Burkholderia cepacia based on its biochemical and physiological characteristics and confirmed by the cellular fatty acid composition and Biolog data as well as 16S rRNA gene sequence analysis. The bacterial isolates caused similar symptoms when inoculated onto fruits of apricot. In addition, European plum, Japanese plum, nectarine and kiwifruit were susceptible to the B. cepacia pathogen. However, the B. cepacia pathogen failed to cause any visible symptoms when it was inoculated onto 16 other fruits. This is the first report of a bacterial disease of apricot caused by B. cepacia in China.
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An analytical model for PVC-FRP confined reinforced concrete columns under low cyclic loading
Yuan Fang,Feng Yu,Anchun Chen,Shilong Wang,Guoshi Xu 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.2
Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.
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