Vertical Vibration of Strip Mill with the Piecewise Nonlinear Constraint arising from Hydraulic Cylinder

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).

How “Foreign Influencer” Present Compelling Chinese Stories--Take “Chris”, a short video blogger in Tik Tok, as an example

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.

Puzzle and Challenge in Routine Extrahepatic Bile Duct Resection for Advanced Gallbladder Carcinoma

Liu Fei,Li Fu-Yu 거트앤리버 소화기연관학회협의회 2020 Gut and Liver Vol.14 No.6

Study on the propagation mechanism of stress wave in underground mining

Fei Liu,Lianghui Li 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.2

For the influence of the propagation law of stress wave at the coal-rock interface during the pre-blasting of the top coal in top coal mining, the ANSYS-LS/DYNA fluid-solid coupling algorithm was used to numerical calculation and the lifedeath element method was used to simulate the propagation of explosion cracks. The equation of the crushing zone and the fracturing zone were derived. The results were calculated and showed that the crushing radius is 14.6 cm and the fracturing radius is 35.8 cm. With the increase of the angles between the borehole and the coal-rock interface, the vibration velocity of the coal particles and the rock particles at the interface decreases gradually, and the transmission coefficient of the stress wave from the coal mass into the rock mass decreases gradually. When the angle between the borehole and the coal-rock interface is 0°, the overall crushing degree is about 11% and up to the largest. With the increase of the distance from the charge to the coal-rock interface, the stress wave transmission coefficient and the crushing degree of the coal-rock are gradually decreased. At the distance of 50 cm, the crushing degree of the coal-rock reached the maximum of approximately 12.3%.

An Optimization Algorithm for Solving High-Dimensional Complex Functions Based on a Multipopulation Cooperative Bare-Bones Particle Swarm

Liu Cong,Liu Yunqing,Wu Tong,Yan Fei,Zhang Qiong 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

The particle swarm optimization (PSO) algorithm can easily become trapped in a local optimum when the objective function to be optimized is high-dimensional and complex. A multipopulation, cooperative, bare-bones particle swarm optimization (MCBBPSO) algorithm is proposed to solve this problem. In MCBBPSO, three types of parallel cooperative learning populations are used to optimize the objective function. By adding disturbance factors and adopting an elite reverse learning strategy, the optimization ability of the algorithm is increased. Through the “mirror wall” method, the cross-boundary particles are processed to reduce the loss of particle resources. Experiments using the CEC2013 standard test functions demonstrate the convergence accuracy and speed of the algorithm on high-dimensional and complex objective functions. Finally, MCBBPSO is applied to perform parameter optimization in support vector regression (SVR), and short-term wind speeds are then predicted using the optimized SVR approach to reduce resource consumption in a power grid.

The Cooperative Effect Analysis when Nanoparticles Enter a Biological Cell

Fei Liu,Dan Wu,Ken Chen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4

The nanoparticle (NP) is one of the most used nanostructures in biomedicine. The Np–biomembrane interface plays an important role in delivering NPs into a living biological cell. While most researchers focus on the interaction between a single Np and a cell membrane, we pay attention to the NP–biomembrane interaction when a cluster of NPs are put into a biological cell together, and analyze the cooperative effect of these NPs. We find that the NPs would not enter the cell individually, but have a trend to form an aggregation to reduce the repel force from the cell membrane. The dissipative particle dynamics simulation shows that the NP aggregation may have three interactive states with the membrane: adhere on the surface of the cell, uptaken by the membrane and enter the cell. We propose to use catalytic (CA) particles which are not sensitive to the membrane to reduce the driving force required in NP delivery. Energy analysis demonstrates that the introduced (CA) particles can decrease the free energy gap between the inside and the outside of the membrane, and increase the success rate of NPs entering the cell.

Iron oxide/MCM-41 mesoporous nanocomposites and their magnetorheology

Liu, Ying Dan,Park, Bong Jun,Fang, Fei Fei,Choi, Hyoung Jin,Ahn, Wha-Seung Springer-Verlag 2013 Colloid and polymer science Vol.291 No.8

Population genetics reveals new introgression in the nucleus herd of min pigs

Liu Tianxin,Ji Dongqing,Li Xinyuan,Liu Jiadong,Xu Fei,Miao Zhiying,Chang Yang,Tian Ming,Xu Chunzhu 한국유전학회 2024 Genes & Genomics Vol.46 No.4

Objective Min pigs are a unique genetic resource among local pig breeds in China. They have more excellent characteristics in cold and stress resistance, good meat quality, and a high reproductive rate. However, the genetic structure and driving factors remain unclear in the nucleus herd. In this study, the genetic diversity of Min pigs was studied to reveal the formation mechanism of its unique genetic structure. We hope to protect and develop the genetic resources of Min pigs. Methods We analyzed different types of genes to identify the genetic structure and gene introgression pattern of Min pigs. The nuclear DNA dataset includes information on 21 microsatellite loci and 6 Y-chromosome genes, and the mitochondrial D-loop gene is selected to represent maternal lineages. The above genes are all from the nucleus herd of Min pigs. Results The results of genetic structure identification and analysis of potential exogenous gene introgression patterns indicate that the nucleus herd of Min pigs maintains a high level of genetic diversity (polymorphism information content = 0.713, expected heterozygosity = 0.662, observed heterozygosity = 0.612). Compared with other Asian pig breeds, the formation of Min pig breeds is more special. Gene introgression from European pig breeds to Min pigs has occurred, which is characterized by complete introgression of paternal genes and incomplete introgression of maternal genes. Conclusion Gene introgression caused by cross-breeding is not the main factor leading to the formation of the current genetic structure of Min pigs, but this process has increased the level of genetic diversity in the nucleus herd. Compared with the influence of gene introgression, our research suggest that artificial selection and environmental adaptive evolution make Min pigs form unique genetic characteristics. Objective Min pigs are a unique genetic resource among local pig breeds in China. They have more excellent characteristics in cold and stress resistance, good meat quality, and a high reproductive rate. However, the genetic structure and driving factors remain unclear in the nucleus herd. In this study, the genetic diversity of Min pigs was studied to reveal the formation mechanism of its unique genetic structure. We hope to protect and develop the genetic resources of Min pigs. Methods We analyzed different types of genes to identify the genetic structure and gene introgression pattern of Min pigs. The nuclear DNA dataset includes information on 21 microsatellite loci and 6 Y-chromosome genes, and the mitochondrial D-loop gene is selected to represent maternal lineages. The above genes are all from the nucleus herd of Min pigs. Results The results of genetic structure identification and analysis of potential exogenous gene introgression patterns indicate that the nucleus herd of Min pigs maintains a high level of genetic diversity (polymorphism information content = 0.713, expected heterozygosity = 0.662, observed heterozygosity = 0.612). Compared with other Asian pig breeds, the formation of Min pig breeds is more special. Gene introgression from European pig breeds to Min pigs has occurred, which is characterized by complete introgression of paternal genes and incomplete introgression of maternal genes. Conclusion Gene introgression caused by cross-breeding is not the main factor leading to the formation of the current genetic structure of Min pigs, but this process has increased the level of genetic diversity in the nucleus herd. Compared with the influence of gene introgression, our research suggest that artificial selection and environmental adaptive evolution make Min pigs form unique genetic characteristics.

An Improved Method to Integrate Low-Cost Sensors for the Navigation of Small UAVs

Fei Liu,Jie Li,Chang Liu,Ji Zhao 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

According to the specific application of small low-cost UAVs (Unmanned Air Vehicles), an improved method integrating MEMS gyro, MEMS accelerometer and magnetometers is proposed. Firstly, according to the sensory measurements, navigation information including two sets of Euler angles and the triad of velocity can be acquired. Subsequently, a simplified state space equation without modeling the body angular motion is established and a standard linear observation model is derived to avoid the nonlinear problems. A Correlated Extended Kalman Filter (CEKF) is adopted to improve the performance. Finally, the proposed method is verified using data collected from a flight test. The results show that the proposed method has significantly improved the performance of this integrated system.

Graphene-based electrochemical biosensor for pathogenic virus detection

Fei Liu,Ki Seok Choi,박태정,이상엽,서태석 한국바이오칩학회 2011 BioChip Journal Vol.5 No.2

A graphene based biosensor system is presented for performing highly sensitive pathogenic virus detection. A free-standing conductive graphene film was prepared as a novel electrochemical sensor through two steps: synthesis of a graphene oxide (GO) film from GO colloidal suspensions by using a speed vacuum concentrator and thermal annealing process at 900℃ with H2/Ar flow to generate a reduced GO film. The resultant graphene film shows an excellent electron transfer property on the surface in the [Fe(CN)_6]^(3-)/^(4-) redox system and is used as a working electrode in the electrochemical biosensor. The surface of graphene is modified with pyrene derivatives,and then covalently linked with virus-specific antibodies. The target cell, rotavirus, is captured on the graphene film through antibody-antigen interaction, and the entire process was monitored by cyclic voltammetric responses. A 10^5 pfu/mL of input cells is detected with ca. 30.7% sensitivity, and ca. 1.3% sensitivity is measured with 10³ pfu/mL of input cells, demonstrating that graphene film based electrode can be applied for electrochemical biosensor.