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Fei Liu,Bin Liu,Hao-ran Liu,Yan-ling Gong,Song-jun Wang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
Vertical vibration model of strip mill is established by considering piecewise nonlinear constraint arising from hydraulic cylinder. The approximate analytical solution of the model is obtained by incremental harmonic balance (IHB) method. The harmonic frequencies not conducive to stability are produced because the nonlinearity of the piecewise constraint. Bifurcation behavior of the system changes with external excitation amplitude and frequency ratio, intermittent chaos and periodic window are appeared alternately, the chaos region enlarged with the increasing piecewise interval. Compared with the piecewise linear constraint, the region of chaotic motion is widened obviously under the nonlinear constraint. Moreover, the critical condition of bifurcation and chaos behavior can be obtained from maximum Lyapunov exponent (MLE).
Liu Jian(Jian Liu),Fei Jingying(Jingying Fei),Lv Mingkang(Mingkang Lv) 아시아사회과학학회 2022 International Science Research Vol.2 No.3
In recent years, a large number of excellent foreign short video bloggers have been active on major social media platforms, comparing the differences between Chinese and Western cultures, introducing Chinese traditional culture and customs to followers, and becoming a new force in telling Chinese stories. This paper takes the short video blogger “Chris” and his short videos as the research object, and analyze how “foreign influencer” tells Chinese stories in the new media environment, which brings new inspiration for telling Chinese stories and spreading Chinese voices well in the new media environment.
Measurement and Evaluation of the Ellipsoid Deviation in Cartesian Coordinates
Fei Liu,Lin Liang,Guanghua Xu,Chenggang Hou,Dan Liu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.11
Ellipsoid part is now increasingly applied to the product manufacturing, while the high-quality ellipsoid part depends not only on the manufacturing and machining techniques, but also on the adopted measurement and evaluation approaches. Based on the typical quadratic surface, an evaluation method of the least squares ellipsoid deviation is proposed in this paper to quantify the form deviation of measured ellipsoid. The method can overcome the weakness of the low measurement adaptability compared with other evaluation methods. With obtaining the coefficients of surface equation to replace the linear superposing of the coordinates of measured points, the measurement error existing in the coordinates of measured points is homogenized and reduced effectively, which prompts to obtain the accurate measurement result. Finally, the results from experimental verifications show that the proposed method is effective for the measurement and evaluation of the ellipsoid deviation in Cartesian coordinates, and the adaptability is also a significant advantage in the measurement and evaluation of geometry deviation.
Liu Fei,Liu Fengqing,Qin Qin,Zou Jing,Jiang Jizhou 한국탄소학회 2023 Carbon Letters Vol.33 No.3
The carbon-containing molecule can be used as an NMR probe to explore the acidic and structural features of various catalytic materials. Thereinto, although mesityl oxide (MO) has been extensively employed to determine the acidity of solution and ionic liquid systems, could it be utilized to characterize the acidic properties of solid acid catalysts? In this work, on the basis of a series of isolated Brønsted and Lewis acid models with varied acid strengths, the adsorption configurations and corresponding 13C chemical shifts of adsorbed MO molecules have been comprehensively studied by means of a theoretical investigation approach. Among them, both the 13C chemical shift difference between β and α carbon atoms (Δδ), and the 13C chemical shift of β carbon atoms (δ13Cβ) in adsorbed MO molecules were explicitly demonstrated to be closely related to the intrinsic acid strength of Brønsted acid sites. These correlations could be utilized to quantitatively scale the Brønsted acid strength of solid acid catalysts. Besides, a moderate relationship was theoretically derived for the relevant 13C NMR parameters and intrinsic Lewis acid strength.
Fei Fei Fang,Ying Dan Liu,Hyoung Jin Choi IEEE 2009 IEEE transactions on magnetics Vol.45 No.6
<P>Carbonyl iron (CI)-based magnetorheological (MR) fluid exhibits serious dispersion defect due to large density mismatch between CI particles and continuous medium, which obviously restricts further MR application. Thus, various modifications on CI particles have been explored, among which embedding CI particles within polymer matrix attracted much attention because the density of fabricated polymer/CI particles got considerably low, consequently enhancing the dispersion stability. In this paper, a more thermal stable polymer, polycarbonate (PC) with high strength, toughness, and heat resistance was adopted as polymer matrix, in which CI particles were randomly embedded via a facile solvent casting method. The embedding structure and density were confirmed by SEM/OM images and pycnometer, respectively. Finally, MR characterization was investigated.</P>
Static Var Generator Based on Accurate Linearization Combined with Sliding Mode Controller
Liu Fei,Wang Xueyan,Huang Xinyi,Yan Honglin,Huang Xiangdong,Pan Hongguang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5
The active and reactive current are hard to be decoupled completely with strong robustness when the traditional proportional integral (PI) algorithm is adopted to feedforward decoupling control for static var generator (SVG). This paper proposed a compound control strategy for SVG based on precise linearization and sliding mode control (SMC). To be specifi c, fi rst, the theory of diff erential geometry is used to prove that the mathematical model of SVG satisfi es the necessary and suffi - cient condition of precise linearization. Second, the precise linearized high-order system of SVG was transformed into two completely independent decoupled fi rst-order linear systems, and realize complete decoupling of active current and reactive current. Finally, SMC was used to design both the voltage outer loop and the current inner loop. Simulations ware carried out for the SVG mathematical model under three conditions which were inductive load, capacitive load and sudden change load. The results of those simulation showed that the controller designed by the proposed control strategy has the advantages of quick reactive power compensation, strong robustness and anti-interference performance.
Liu Jing,Ke Pingyang,Guo Haokun,Gu Juan,Liu Yanling,Tian Xin,Wang Xuefeng,Xiao Fei 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-
The pathophysiological mechanisms underlying epileptogenesis are poorly understood but are considered to actively involve an imbalance between excitatory and inhibitory synaptic transmission. Excessive activation of autophagy, a cellular pathway that leads to the removal of proteins, is known to aggravate the disease. Toll-like receptor (TLR) 7 is an innate immune receptor that regulates autophagy in infectious and noninfectious diseases. However, the relationship between TLR7, autophagy, and synaptic transmission during epileptogenesis remains unclear. We found that TLR7 was activated in neurons in the early stage of epileptogenesis. TLR7 knockout significantly suppressed seizure susceptibility and neuronal excitability. Furthermore, activation of TLR7 induced autophagy and decreased the expression of kinesin family member 5 A (KIF5A), which influenced interactions with γ-aminobutyric acid type A receptor (GABAAR)-associated protein and GABAARβ2/3, thus producing abnormal GABAAR-mediated postsynaptic transmission. Our results indicated that TLR7 is an important factor in regulating epileptogenesis, suggesting a possible therapeutic target for epilepsy.
Study on the propagation mechanism of blast waves using the ultra-dynamic strain test system
Fei Liu,Mingzhong Gao,Ziru Guo,Changtai Zhou,Jun Wang 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.1
The propagation mechanism of blast waves in rock materials is hard to test. This paper explores the propagation mechanism of blast-induced strain waves in coal and rock using physical modeling together with numerical modeling. The results show that the strain waves in coal blocks were weaker than that in mortar blocks under the same blast loading. With increasing distance, the strain waves induced by the shock wave show a slighter decrease in coal blocks in the radial direction, but show a stable tendency in coal blocks and a slight decrease in mortar blocks in the tangential direction. However, the strain waves induced by the explosion gas show a stable tendency in both coal and mortar blocks. The actuation duration of strain waves in coal blocks is longer than that in mortar blocks. The gap of the radial strain waves induced by shock waves is narrowed gradually and moved similarly equal to each other both in coal and mortar blocks with increasing distance. The simulated results show similar values in coal and mortar blocks as compared with the test results. The coal blocks have a better fracturing effect than that of the mortar blocks in the physical test.
Study on Electro-Spark Deposition Welding of Ultra-thin Sheet of Ti-6.5Al-1Mo-1 V-2Zr Alloy
Fei Liu,Tao Chen,Lihui Pang,Kuijing Song,Yucheng Wu 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.10
In this work, butt welding experiment of Ti-6.5Al-1Mo-1 V-2Zr alloy sheet of 0.5 mm thickness was performed via electro-spark deposition method. The results of the experiment indicate that the reactive titanium alloy’s surface is free from oxidation without trailing shielding protection due to low heat input and rapid thermal cycles associated with the process. The fusion zone is mainly composed of equiaxed microstructure of martensite α′ and α dual phases, wherein the amount of α′ in the central joint is higher than that adjacent to the base metal. The maximum tensile strength of the welded joint can reach 1187 MPa, which is 95% of the base metal. Besides, the joint shows obvious plastic deformation before fracture. The findings have demonstrated the possibility of widely applying the welding methodology to thin sheets of titanium alloys.