An experimental study of the mechanical performance of different types of girdling beams used to elevate bridges

Fangyuan Li,Wenhao Li,Peifeng Wu 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.4

Girdling underpinning joints are key areas of concern for the pier-cutting bridge-lifting process. In this study, five specimens of an underpinning joint were prepared by varying the cross-sectional shape of the respective column, the process used to treat the beam-column interface (BCI), and the casting process. These specimens were subsequently analyzed through static failure tests. The BCI was found to be the weakest area of the joint, and the specimens containing a BCI underwent punching shear failure. The top of the girdling beam (GB) was subjected to a circumferential tensile force during slippage failure. Compared to the specimens with a smooth BCI, the specimens subjected to chiseling exhibited more pronounced circumferential compression at the BCI, which in turn considerably increased the shear capacity of the BCI and the ductility of the structure. The GB for the specimens containing a column with a circular cross-section exhibited better shear mechanical properties than the GB of other specimens. The BCI in specimens containing a column with a circular cross-section was more ductile during failure than that in specimens containing a column with a square cross-section.

Moving Rate of Positive Patient Results as a Quality Control Tool for High-Sensitivity Cardiac Troponin T Assays

Li Tingting,Cao Shunwang,Wang Yi,Xiong Yujuan,He Yuting,Ke Peifeng,Huang Xianzhang 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.1

Background: A small shift in high-sensitivity cardiac troponin T (hs-cTnT) assays can lead to different result interpretation and consequent patient management. We explored whether a small bias could be detected using conventional internal quality control (QC) procedures, evaluated the performance of moving average (MA)-based QC procedures, and proposed a new QC procedure based on the moving rate (MR) of positive patient results of hs-cTnT assays. Methods:The ability of conventional QC to detect a 5 ng/L bias was examined using the13s/ 22s/R4s multi-rule procedure as deviation rules.We developed MA and MR procedures for the hs-cTnT assay using eight months of patient data. The performance of different MA or MR procedures was investigated by calculating the median number of patient samples affected until a bias introduced into the dataset was detected (MNPed). After comparing the MNPed across different procedures, we selected an optimal MA or MR procedure for validation. Validation graphs were plotted using the minimum, median, and maximum number of results affected until bias detection. Results: Our conventional QC procedures could not detect a positive bias of 5 ng/L. When a positive bias was introduced, MNPed was much higher using MA than using MR, with cut-off values of 5 ng/L and 14 ng/L, respectively. MR validation charts for optimal procedures provided insight into the MR performance. Conclusions: The MR procedure could detect different errors with few false alarms. In the hs-cTnT assay, the MR procedure with a smaller cut-off value outperformed MA and conventional QC procedures for small bias detection.

Analysis and monitoring on jacking construction of continuous box girder bridge

Fangyuan Li,Peifeng Wu,Xinfei Yan 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.1

It is hard to guarantee the strict synchronization of all the jacking-up points in the integral jacking of a large-span continuous box girder bridge. This paper took the Hengliaojing Bridge as background, which need jacking up as an object with 295m length and more than 10,000tons weight, adopted 3D software to calculate the unsynchronized jacking-up working conditions, and studied the relationships between the unsynchronized vertical difference and the girder’s deformation behaviour. The aim is to verify the maximum value of the unsynchronized vertical difference, and guide the construction and ensure safety. The monitoring system with its contents is introduced corresponding to the analysis. The results of the deck relative elevations prove that it is difficult to avoid the deck torsional deformation for jacking different; especially the side span shows more deformations for its smaller stiffness. The maximum difference is smaller than the limited value with acceptable stresses in the sections. The jacking heights of the pier in each construction step are controlled regularly according to the design. The shifting of the whole bridge in longitudinal direction is smaller than in transverse direction. The several beginning steps are the key to adjust their support reactions. This study is one parts of the fundamental research for the code “Technical specification for bridge jacking-up and reposition of China”. The whole synchronous jacking project of the main bridge set a world record by the World Record Association for the whole bridge jacking project with the longest span of the world.

Experimental study on the cable rigidness and static behaviors of AERORail structure

Fangyuan Li,Peifeng Wu,Dongjie Liu 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.5

This paper presented a new aerial platform-AERORail for rail transport and its structure evolution based on the elastic stiffness of cable; through the analysis on the cable properties when the cable supported a small service load with high-tensile force, summarized the theoretical basis of the AERORail structure and the corresponding simplified analysis model. There were 60 groups of experiments for a single naked cable model under different tensile forces and different services loads, and 48 groups of experiments for the cable with rail combined structure model. The experimental results of deflection characteristics were compared with the theoretical values for these two types of structures under the same conditions. It proved that the results almost met the classical cable theory. The reason is that a small deflection was required when this structure was applied. After the tension increments tests with moving load, it is verified that the relationships between the structure stiffness and tension force and service load are simple. Before further research and applications are made, these results are necessary for the determination of the reasonable and economic tensile force, allowable service load for the special span length for this new platform.

Global Synchronization in Finite-time of Fractional-order Complex-valued Delayed Hopfield Neural Networks

Xinxin Zhang,Peifeng Niu,Nan Liu,Guoqiang Li 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.2

This paper deals with the synchronization issue of fractional-order complex-valued Hopfield neural networkswith time delay. In this paper, by means of properties of the fractional-order inequality, such as H¨ olderinequality and Gronwall inequality, sufficient conditions are presented to guarantee the finite-time synchronizationof the fractional-order complex-valued delayed neural networks when 1=2 g < 1 and 0 <g < 1=2. Finally, twonumerical simulations are provided to show the effectiveness of the obtained results.

Low voltage ride-through control strategy for virtual synchronous generators based on virtual self-inductive flux linkage

Shi, Kai,Li, Tong,Ren, Mingwei,Xu, Peifeng The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.5

Virtual synchronous generators (VSGs), with the operational characteristics of synchronous generators (SGs), have been employed in renewable energy generation grid-connected systems to solve the problem of insufficient equivalent inertia, which is caused by the high permeability of distributed generation systems in the grid. However, a VSG does not possess low voltage ride-through (LVRT) capability. A novel LVRT control strategy for a VSG based on virtual self-inductive flux linkage is proposed in this paper. First, the electromagnetic transient response mechanism of a SG under grid faults is analyzed in detail. Then, a memory and retention strategy are proposed to simulate the effect of the switch law. Furthermore, the virtual q-axis armature self-inductance is introduced into the VSG and a virtual self-inductive magnetic chain is utilized to block the change of the transient fault current. This helps the inverter adjust the output voltage quickly. In addition, under the premise of meeting the reactive power margin, the reactive power compensation strategy is optimized to achieve a quick response in terms of the reactive power compensation of grid faults, which is helpful for realizing the LVRT of a VSG. Finally, the feasibility and effectiveness of the proposed LVRT method are verified by thorough simulation results.

The Functional Roles of Lactobacillus acidophilus in Different Physiological and Pathological Processes

( Huijuan Gao ),( Xin Li ),( Xiatian Chen ),( Deng Hai ),( Chuang Wei ),( Lei Zhang ),( Peifeng Li ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.10

Probiotics are live microorganisms that can be consumed by humans in amounts sufficient to offer health-promoting effects. Owing to their various biological functions, probiotics are widely used in biological engineering, industry and agriculture, food safety, and the life and health fields. Lactobacillus acidophilus (L. acidophilus), an important human intestinal probiotic, was originally isolated from the human gastrointestinal tract and its functions have been widely studied ever since it was named in 1900. L. acidophilus has been found to play important roles in many aspects of human health. Due to its good resistance against acid and bile salts, it has broad application prospects in functional, edible probiotic preparations. In this review, we explore the basic characteristics and biological functions of L. acidophilus based on the research progress made thus far worldwide. Various problems to be solved regarding the applications of probiotic products and their future development are also discussed.

Study on Strength Characteristics and Microstructure of Completely Decomposed Migmatitic Granite

Song Yan,Hua Tang,Zhenjun Wu,Sitao Li,Peifeng Li 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1

Migmatitic granite is the product of mixed lithification and granitization, and completely decomposed migmatitic granite (CDMG) was formed after weathering. The engineering properties of CDMG are complex, and its engineering properties are complex after weathering, and water content has a great influence on the properties of (CDMG). Due to its loose structure and strong heterogeneity, it is difficult to determine its strength characteristics by conventional test methods. In the paper triaxial and micro-CT test were conducted to study the relationship between shear strength and microstructure of CDMG under different water content. The results show that with the increase of water content from 6% to 14%, the internal friction angle decreases from 31.8° to 27.3°, and the cohesion first increases from 76.5 kPa to 94.3 kPa and then decreases to 77.7 kPa. This is because the sliding friction coefficient between coarse particles decreases with the increase of water film thickness on the surface of particles, and the occlusal effect between coarse particles weakens and the displacement adjustment is easier during the triaxial loading process. Under different water content, the shear strength of CDMG is not sensitive to particle structure parameters including particle size, particle morphology and particle arrangement. The particle analysis results of post-test sample show that the crushing proportion of coarse particles increases with the increase of the internal friction angle. The clay minerals produce differential expansion potential with the increase of water content, and the porosity and pore connectivity first decrease and then increase. Cohesion has a linear relationship with porosity and pore connectivity. With the increase of porosity from 23.95% to 26.95%, cohesion decreases linearly by 17%. These results indicate that the internal friction angle of CDMG can be inferred by water content, and the cohesion can be inferred by porosity and pore connectivity obtained by microstructure analysis.

Circular RNA ROCK1, a novel circRNA, suppresses osteosarcoma proliferation and migration via altering the miR-532-5p/PTEN axis

Liu Yize,Qiu Guanzhen,Luo Yinzhou,Li Shanshan,Xu Yeqiu,Zhang Yuanzhuang,Hu Jiayuan,Li Peifeng,Pan Hai,Wang Yong 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

As the most prevalent bone tumor in children and adolescents, the pathogenesis and metastasis of osteosarcoma (OS) remain largely unclear. Here, we investigated the expression and function of a novel circular RNA (circRNA), circROCK1-E3/E4, which is back-spliced from exons 3 and 4 of Rho-associated coiled-coil containing protein kinase 1 (ROCK1) in OS. We found that circROCK1-E3/E4, regulated by the well-known RNA-binding protein quaking (QKI), was downregulated in OS and correlated with unfavorable clinical features of patients with OS. Functional proliferation and cell motility assays indicated that circROCK1-E3/E4 serves as a tumor suppressor in OS cells. Mechanistically, circROCK1-E3/E4 suppressed proliferation and migration by upregulating phosphatase and tensin homolog (PTEN) through microRNA-532-5p (miR-532-5p) sponging. In the constructed nude mouse model, circROCK1-E3/E4 inhibited tumor growth and lung metastasis in vivo. This study demonstrates the functions and molecular mechanisms of circROCK1-E3/E4 in the progression of OS. These findings may identify novel targets for the molecular therapy of OS.