Study on Dynamic Characteristics and Load Sharing of a Herringbone Planetary Gear with Manufacturing Errors

Fei Ren,Datong Qin,Teik Chin Lim,류성기 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

In this paper, a new and generalized dynamic model for a herringbone planetary gear train (HPGT) is proposed to investigate thefree and forced vibration characteristics, as well as load sharing characteristics by employing the lumped-parameter approach. Theproposed model takes into account manufacturing eccentric errors of the components and tooth profile errors of all gears. The modelcan be used for the vibration performance and dynamic load sharing analysis of the HPGT with different types of manufacturingerrors and arbitrary number of planets. The free and forced vibration, as well as the load sharing of an HPGT with three planetsare numerically computed with the model presented, and these are analyzed respectively in time domain and frequency domain. Theeffects of the manufacturing eccentric error and tooth profile error as well as component float on load sharing are discussedrespectively. Results indicate that manufacturing errors have an impact on dynamic characteristics and load sharing. The float cansignificantly reduce the load sharing coefficient of the system.

A kinematic mechanism for positive feedback between synoptic eddies and NAO

Ren, Hong-Li,Jin, Fei-Fei,Kug, Jong-Seong,Zhao, Jing-Xia,Park, Juhyun American Geophysical Union 2009 Geophysical research letters Vol.36 No.11

Identification of novel rheumatoid arthritis-associated MiRNA-204-5p from plasma exosomes

Wu Long-Fei,Zhang Qin,Mo Xing-Bo,Lin Jun,Wu Yang-Lin,Lu Xin,He Pei,Wu Jian,Guo Yu-Fan,Wang Ming-Jun,Ren Wen-Yan,Deng Hong-Wen,Lei Shu-Feng,Deng Fei-Yan 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Rheumatoid arthritis (RA) is an autoimmune disease characterized by infiltration of immune cells in the synovium. However, the crosstalk of immune cells and synovial fibroblasts is still largely unknown. Here, global miRNA screening in plasma exosomes was carried out with a custom microarray (RA patients vs. healthy controls = 9:9). A total of 14 exosomal miRNAs were abnormally expressed in the RA patients. Then, downregulated expression of exosomal miR-204-5p was confirmed in both the replication (RA patients vs. healthy controls = 30:30) and validation groups (RA patients vs. healthy controls = 56:60). Similar to the findings obtained in humans, a decreased abundance of exosomal miR-204-5p was observed in mice with collagen-induced arthritis (CIA). Furthermore, Spearman correlation analysis indicated that plasma exosomal miR-204-5p expression was inversely correlated with disease parameters of RA patients, such as rheumatoid factor, erythrocyte sedimentation rate, and C-reactive protein. In vitro, our data showed that human T lymphocytes released exosomes containing large amounts of miR-204-5p, which can be transferred into synovial fibroblasts, inhibiting cell proliferation. Overexpression of miR-204-5p in synovial fibroblasts suppressed synovial fibroblast activation by targeting genes related to cell proliferation and invasion. In vivo assays found that administration of lentiviruses expressing miR-204-5p markedly alleviated the disease progression of the mice with CIA. Collectively, this study identified a novel RA-associated plasma exosomal miRNA-204-5p that mediates the communication between immune cells and synovial fibroblasts and can be used as a potential biomarker for RA diagnosis and treatment.

Physically-Based Constitutive Modelling of As-Cast CL70 Steel for Hot Deformation

Fei Chen,Xiaodong Zhao,Jinyu Ren,Huiqin Chen,Xiaofeng Zhang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

In order to conduct numerical simulation of plasticity forming and confirm the processing parameters of heat deformationfor as-cast CL70 steel, the hot deformation behaviors of as-cast CL70 steel were studied by isothermal compression testswhich used a Gleeble-1500D thermal mechanical simulation tester for the deformation temperatures ranging from 1173 to1523 K and the strain rates ranging from 0.001 to 1 s−1. Flow stress curves of the steel were obtained under high temperature. The flow stress constitutive models of the work hardening-dynamical recovery period and dynamical recrystallizationperiod were established for as-cast CL70 steel. In work hardening-dynamic recovery period, the flow stress was predicted byemploying the evolution rule of dislocation density in the constitutive model. In dynamic recrystallization period, the flowstress after the critical strain was predicted by employing the dynamic recrystallization kinetics in the constitutive model. To improve the prediction accuracy of the model, the dynamic recovery coefficient is modified in the traditional physicallybasedconstitutive model. The results indicate that the proposed physically-based constitutive model has high accuracy inpredicting the flow stress under hot deformation for as-cast CL70 steel.

The Modeling Methods of Heavy NC Machine Tool Bolt Joint Based on Virtual Media

Ren Sheng-Le,Gao Fei,Dai Ye,Wang Peng,Cheng Tian-Yu 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.9

The Department of Heavy NC machine tool has a great influence on the performance of machine tools. The 30%-50% static stiffness, more than 50% of the dynamic stiffness depends on the combining part, and the influence on damping reached 90%.Machine tool with the Department of static and dynamic performance directly determines the accuracy and reliability of Heavy NC machine tool. Therefore, in conjunction with the Department of research and design of Heavy NC machine tool is very important. In this paper, based on Hertz contact theory, the contact at the micro level, considering the combination form of machine tool, and the machine joints as a virtual media simulation, a combination of virtual media framework, and calculation of characteristic parameters of the virtual material, then use the ANSYS Workbench to solve the combination of the natural frequency of the whole, the first five order modal extraction. Using modal test technology, get the specimens of natural frequency and damping of the true value, natural frequency are compared with theory, prove the formula of virtual media is reliable, can be used in the modeling of heavy machine tool.

Ascorbate Levels and Activities of Enzymes Related to the Glutathione-Ascorbate Cycle in Fruits of Chinese Persimmon Cultivars

Fei Pu,Xiaolin Ren 한국원예학회 2014 Horticulture, Environment, and Biotechnology Vol.55 No.4

We evaluated differences in ascorbic acid (AsA) and glutathione (GSH) contents and activities of enzymesinvolved in the AsA metabolism in fruits of 20 cultivars of Chinese persimmon (Diospyros kaki). The total AsAcontent ranged from 3.85 (cv. Yangshuohuoshi) to 83.02 μmol·g-1 FW (cv. Wangmoshuishi), with an average of 36.69μmol·g-1 FW across the 20 cultivars. The total GSH content ranged from 0.205 (cv. Yangshuohuoshi) to 0.815 μmol·g-1 FW(cv. Mimiguan) with an average 0.533 μmol·g-1 FW. There were significant differences in activities of dehydroascorbatereductase (DHAR, EC 1.8.5.1), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), ascorbate peroxidase (APX,EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) in fruits among the 20 cultivars. The AsA content wassignificantly positively correlated with MDHAR and DHAR activities, but not with GSH and hydrogen peroxide(H2O2) contents or APX activity. These results indicated that both MDHAR and DHAR, especially MDHAR, playimportant roles in maintaining the AsA redox state by reducing oxidized AsA back to AsA and the AsA level mainlydepends on biosynthesis, rather than recycling.

Model analysis, simplified control and sensitivity verification of modular multilevel DC-DC converter with parallel branches

Ren, Qiang,Xiao, Fei,Ai, Sheng The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.2

In view of the modular multilevel topology with its uses in medium-voltage DC vessel integrated power systems, this paper deals with typical modular multilevel DC-DC converter (MMDC) topologies and AC control methods. In terms of DC control, a brief introduction is first made about a MMDC topology with parallel branches and its static characteristics. Then, an analysis is focused on the modeling of the MMDC and its model simplification. An optimal control strategy is proposed for the simplified model. Finally, the sensitivity of this system to model and parameter uncertainties is verified both theoretically and experimentally. The obtained results show that the proposed MMDC consisting of a heterogeneous full-bridge submodule and a parallel-branch structure can make the submodule voltage self-balancing and the range of output voltage wide. The use of an optimal control strategy based on a simplified model can lead the system to achieve good static and dynamic performance and robustness.

Condition monitoring of inverter power devices based on electromagnetic acoustic emissions

Fei Liu,Chenghao Zeng,Liang Cheng,Yunze He,Yun Bai,Xuefeng Geng,Songyuan Liu,Dantong Ren,Lei Wang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

Unlike conventional voltage and current sensing, this paper studies the use of acoustic emission signals to detect the condition of the power device for a DC–AC inverter. As a relatively new method for monitoring power devices, there are some unknown phenomena in acoustic emissions (also called mechanical stress wave). Therefore, the authors present an experimental setup that is used to analyze acoustic emission signals. Based on experimental results, some interesting points have been found: (1) The generation of a mechanical stress wave is verified for the first time. (2) The time-domain peak value, energy, and rise time of the mechanical stress wave at the turn-on time of a power device are barely affected by the load. Meanwhile, these values decrease with an increase of the load at the turn-off time. (3) The frequency-domain peak value of the mechanical stress wave tends to decrease with an increase of the load, and the peak frequency is barely affected by the load. These mechanical stress analysis results can be utilized for condition monitoring in many applications.

Adjustable and extensible hexagonal acoustic metamaterial cell combining multiple parallel Helmholtz resonators with optional apertures

Fei Yang,Shaohua Bi,Xinmin Shen,Xiaocui Yang,Xinqing Wang,Xiangpo Zhang,Jinhong Xue,Xiaonan Zhang,Qin Yin,Juying Dai,Wenqiang Peng,Jingwei Zhu,Junhong Ren 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

To prevent noise pollution, a hexagonal acoustic metamaterial cell combining multiple parallel Helmholtz resonators with optional apertures is proposed. There were 6 trapezoidal chambers and 6 triangular chambers, and each front panel had 6 different apertures, which meant that there were 6 12 = 2176782336 possible permutations. The distribution of sound pressures obtained by acoustic finite element simulation revealed the acoustic absorption mechanism, which provided effective guidance to alter the absorption capacity. For certain scenarios, the acoustic absorption performance was optimized by the joint combination of artificial neural network and acoustic finite element simulation. Through manufacturing and testing the sample, actual average acoustic absorption coefficients were achieved at 0.6733, 0.7296, 0.8785 and 0.7065 for the target frequency ranges 350-950 Hz, 400-1000 Hz, 500-800 Hz and 350-700 Hz, respectively, with total thickness 40 mm. The tunable acoustic absorption property proved that the hexagonal acoustic metamaterial cell was appropriate for noise reduction with variable frequency ranges.

Polyvinylidene Fluoride Electrospun Fibers Loaded TiO2 for Photocatalytic Degradation and Oil/Water Separation

Fei Sun,Hai-Tao Ren,Shih-Yu Huang,Ting-Ting Li,Hao-Kai Peng,Qi Lin,Ching-Wen Lou,Jia-Horng Lin 한국섬유공학회 2020 Fibers and polymers Vol.21 No.7

In this study, electrospun polyvinylidene fluoride (PVDF)-based nanofibrous membranes embedding TiO2 wereprepared and used for photocatalytic degradation and oil/water separation. The nanofibrous membranes were characterizedby scanning electron microscopy (SEM), transmission electronic microscope (TEM), X-ray diffraction (XRD), Fouriertransform infrared spectroscopy (FTIR) spectroscopy, thermal performance analysis, and oil/water separation analysis. Andthe degradation of rhodamine B dye was also investigated. Results showed that the fiber diameter and thermal stability of themembranes decreased with the increasing of TiO2. Meanwhile, the fiber surface roughness and specific surface areaincreased. The analysis of TEM, XRD and FTIR indicated that TiO2 existed in the PVDF membranes. When the TiO2 contentwas 12 %, the fiber diameter of the membranes was about 110 nm, and the photocatalytic degradation of rhodamine B dyeefficiency was up to 97 %. The reaction rate constant was 0.02057 min-1. At 0.01 MPa vacuum, oil separated from watereffectively, which proves that separation can be easily conducted with a low energy cost. Thus, the prepared membranes havea very high application prospect in the purification of reclaimed water and separation of oil and water.