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On the fatigue performance of Aluminum alloy 2024 scarfed lap joints
W.Z. Yan,H.S. Gao,X. Yuan,F.S. Wang,Z.F. Yue 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.1
A series of fatigue test were carried out on scarfed lap joints (SLJ) using in airfoil siding to explore the effect of structural details, such as rows of rivets, lap angles, on its fatigue performance. Finite element (FE) analysis was employed to explore the effect of lap angle on load transfer and the stress evolution around the rivet hole. At last, the fatigue lives were predicted by nominal stress approach and critical plane approach. Both of the test results and predicted results showed that fatigue life of SLJ was remarkably increased after introducing lap angle into the faying surface. Specimen with the lap angle of 1.68o exhibits the best fatigue performance in the present study.
On the fatigue performance of Aluminum alloy 2024 scarfed lap joints
Yan, W.Z.,Gao, H.S.,Yuan, X.,Wang, F.S.,Yue, Z.F. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.1
A series of fatigue test were carried out on scarfed lap joints (SLJ) using in airfoil siding to explore the effect of structural details, such as rows of rivets, lap angles, on its fatigue performance. Finite element (FE) analysis was employed to explore the effect of lap angle on load transfer and the stress evolution around the rivet hole. At last, the fatigue lives were predicted by nominal stress approach and critical plane approach. Both of the test results and predicted results showed that fatigue life of SLJ was remarkably increased after introducing lap angle into the faying surface. Specimen with the lap angle of $1.68^{\circ}$ exhibits the best fatigue performance in the present study.
Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak
Yan, W,Chen, Z Y,Huang, D W,Hu, Q M,Shi, Y J,Ding, Y H,Cheng, Z F,Yang, Z J,Pan, X M,Lee, S G,Tong, R H,Wei, Y N,Dong, Y B IOP 2018 Plasma physics and controlled fusion Vol.60 No.3
<P>The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s<SUP>−1</SUP> in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.</P>
A fractional approach to the time-temperature dependence of dynamic viscoelastic behavior
Z. L. Li,Y. Qin,B. Sun,C. L. Jia,W. J. Zhang,B. J. Yan,Q. L. Shi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1
Fractional derivative and WLF equation are effective in describing the dynamic behavior and time-temperature effect of viscoelastic damping materials, respectively. These approaches have essentially evolved from the viscoelastic constitutive behavior. Based on such intrinsic relation, a fractional time-temperature superposition principle model (FTTSPM) that integrates the fractional constitutive relation and WLF equation was proposed. The parameters of this model were determined by performing tensile and DMA tests, and the master curves at 5 °C constructed by FTTSPM and WLF equation were compared. The theoretical prediction over the extended frequency span as the master curves was made by using the fractional standard linear solid model (FSLSM) to validate FTTSPM. The numerical results show that FTTSPM conforms to the time-temperature superposition principle. The parameters α and B¢ in this model denote the impact of the material and environment on the shifted factor, respectively. For the storage and loss modulus, the extended frequency obtained by FTTSPM is broader than that obtained by the WLF equation. Moreover, the evaluation of the storage and loss modulus by FTTSPM is much closer to the theoretical prediction compared with that by the WLF equation. Therefore, FTTSPM is a concise and experiment-based approach with a higher precision and greater frequency-extended capacity compared with the WLF equation. However, FTTSPM inevitably faces a vertical shift when non-thermo-rheologically simple materials are considered. The physical mechanism and practical application of FTTSPM will be examined in further research.
Quantitative assessment of offshore wind speed variability using fractal analysis
Z.R. Shu,P.W. Chan,Q.S. Li,Y.C. He,B.W. Yan 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.4
Proper understanding of offshore wind speed variability is of essential importance in practice, which provides useful information to a wide range of coastal and marine activities. In this paper, long-term wind speed data recorded at various offshore stations are analyzed in the framework of fractal dimension analysis. Fractal analysis is a well-established data analysis tool, which is particularly suitable to determine the complexity in time series from a quantitative point of view. The fractal dimension is estimated using the conventional box-counting method. The results suggest that the wind speed data are generally fractals, which are likely to exhibit a persistent nature. The mean fractal dimension varies from 1.31 at an offshore weather station to 1.43 at an urban station, which is mainly associated with surface roughness condition. Monthly variability of fractal dimension at offshore stations is well-defined, which often possess larger values during hotter months and lower values during winter. This is partly attributed to the effect of thermal instability. In addition, with an increase in measurement interval, the mean and minimum fractal dimension decrease, whereas the maximum and coefficient of variation increase in parallel.
Cloning and characterization of a novel GIGANTEA gene in sweet potato
Tang, W.,Yan, H.,Su, Z.x.,Park, S.C.,Liu, Y.j.,Zhang, Y.g.,Wang, X.,Kou, M.,Ma, D.f.,Kwak, S.S.,Li, Q. Gauthier-Villars ; Elsevier Science Ltd 2017 Vol. No.
<P>The transition from vegetative to reproductive growth, a key event in the lifecycle of a plant, is affected by environmental stresses. The flowering-time regulator GIGANTEA (GI) may be contributing to susceptibility of the regulation of photoperiodic flowering, circadian rhythm control, and abiotic stress resistance in Arabidopsis. However, the role of GI in sweet potato remains unknown. Here, we isolated and characterized a GI gene (IbGI) from sweet potato (Ipomoea batatas [LI Lam). The IbGI cDNA sequence was isolated based on information from a sweet potato transcriptome database. IbGI mRNA transcript levels showed robust circadian rhythm control during the light-dark transition, and the expression of IbGI was stronger in leaves and roots than in stems. IbGI protein is predominantly localized to the nucleus. IbGI expression was upregulated by high temperature, drought, and salt stress but downregulated by cold stress. Overexpressing IbGI in the Arabidopsis gi-2 mutant background rescued its late flowering phenotype and reduced its salt tolerance. Taken together, these results indicate that IbGI shares functions in regulating flowering, the circadian rhythm, and tolerance to some stresses with other GI orthologs. (C) 2017 Elsevier Masson SAS. All rights reserved.</P>
Experimental Study of the Runaway Current in the J-TEXT Tokamak
Y. H. Luo,Z. Y. Chen,X. Q. Zhang,D. W. Huang,W. Jin,Y. H. Huang,Y. Tang,J. C. Li,R. H. Tong,W. Yan,G. Zhuang 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.3
Major plasma disruptions in tokamaks often generate runaway currents, which contain electronswith energies of several tens of megaelectron-volts (MeV). These currents can cause substantialdamage when control is lost and the current hits the limiters or the vessel wall. The interactionbetween the runaway electrons and the impurities inside the plasma results in soft X-ray emission,which can provide detailed information about the runaway generation process and the confinementof runaway electrons. A vertical soft X-ray array at the top of Joint Texas Experimental Tokamak(J-TEXT) was used to study the runaway beams resulting from major disruptions. Runawayelectron production and confinement of runaway current were observed by using soft X-ray images.
Yi, A-L,Yan, L-S,Luo, B,Pan, W,Ye, J,Chen, Z-Y,Lee, J H Optical Society of America 2012 Optics express Vol.20 No.9
<P>Simultaneous all-optical RZ-OOK to NRZ-OOK format conversion for two tributaries in PDM signal is demonstrated utilizing a single section of highly nonlinear fiber through polarization nonlinear loop mirror configuration. Less than 1-dB power penalty is achieved in a 2 ?? 12.5-Gb/s PDM system, and only 1.4-dB SNR penalty is obtained in a 2 ?? 40-Gb/s PDM system.</P>