M-DOF dynamic model for load sharing behavior analysis of PGT

Huimin Dong,Yangyang Wu,Delun Wang,Shaoping Bai 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

A Multi-degree-of-freedom (M-DOF) nonlinear dynamic model for n-pinion Planetary gear train (PGT) is presented in this paper to investigate load sharing behavior of planet gears. In this dynamic model, manufacturing and assembly errors, elastic deformation and time-varying mesh stiffness are considered. Two sets of elastic compatibility equations are proposed to describe compatibility relationship between displacements, errors and elastic deformations. By means of Ishikawa formula, time-varying mesh stiffness of the gear pair is determined. The dynamic motion equations are solved with Runge-Kutta numerical integral method, which yields the displacements and deformations of each component. With the model, dynamic load sharing behavior of planet gears is evaluated. An example of 3-pinion PGT dynamic modeling is included, for which the influence of floating sun gear and adding flexible planet pin on the load sharing characteristics is analyzed.

Modeling, Analysis and Testing of Load Distribution for Planetary Gear Trains with 3D Carrier Pinhole Position Errors

Huimin Dong,Chu Zhang,Shaoping Bai,Delun Wang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.8

A discrete model to study the load distribution behavior of helical planetary gear trains (PGTs) is developed, in which 3D planet position errors, induced by carrier pinhole position errors and tooth modifications, are duly considered. The model adopts a discrete approach with which the planetary gear train is discretized into a series of slice-units in order to ease the problem of gear meshing in 3D cases. In the modelling, compatibility conditions and discrete equilibrium are developed for the coupling among 3D planet position errors, tooth modifications, instantaneous meshing situations, elastic deformations and rigid body spatial motions. Upon the discrete model, a method for analysis of the load distribution is further developed. The influence of 3D planet position errors and tooth modifications on the load distribution was simulated for a helical PGT having three and four planets. Tests on the actual wind turbine PGTs were conducted with results agreed with the simulations obtained, which validate the proposed method.

New Terminal Sliding Mode Consensus Algorithm for Disturbed Second-order Multi-agent Systems

Yan Ren,Huimin Wang,Meixia Yue,Kai Weng,Wei Gao,Ning Liu,Dong Xie 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.8

A finite-time adaptive tracking control algorithm based on non-singular terminal sliding mode (NTSM) is proposed to solve the consensus problem of second-order multi-agent system (MAS) with disturbance. Firstly, a finite-time disturbance observer based on NTSM is introduced to estimate and compensate the disturbance. Then, a NTSM adaptive controller is designed to enhance the robustness of the system, and improve the response speed and tracking accuracy. A proof of the finite-time convergence of the method is given by using Lyapunov theory. Finally, simulation experiments are carried out to demonstrate the effectiveness of the proposed method.

Graphene and graphene‑like carbon nanomaterials‑based electrochemical biosensors for phytohormone detection

Meiqing Yang,Lu Wang,Haozi Lu,Qizhi Dong,Huimin Li,Song Liu 한국탄소학회 2023 Carbon Letters Vol.33 No.5

Phytohormones (plant hormones) are a class of small-molecule organic compounds synthesized de novo in plants. Although phytohormones are present in trace amounts, they play a key role in regulating plant growth and development, and in response to external stresses. Therefore, the analysis and monitoring of phytohormones have become an important research topic in precision agriculture. Among the various detection methods, electrochemical analysis is favored because of its simplicity, rapidity, high sensitivity, and in-situ monitoring. Graphene and graphene-like carbon materials have abundant sources, exhibiting large specific surface area, and excellent physicochemical properties. Thus, they have been widely used in the preparation of electrochemical biosensors for phytohormone detection. In this paper, the research advances of electrochemical sensors based on graphene and graphene-like carbon materials for phytohormone detection have been reviewed. The properties of graphene and graphene-like carbon materials are first introduced. Then, the research advances of electrochemical biosensors (including conventional electrochemical sensors, photoelectrochemical sensors, and electrochemiluminescence sensors) based on graphene and graphene-like carbon materials for phytohormone detection is summarized, with emphasis on their sensing strategies and the roles of graphene and graphene-like carbon materials in them. Finally, the development of electrochemical sensors based on graphene and graphene-like carbon materials for phytohormone detection is prospected.

One-Step CVD Synthesis of Few-Layer SnS2/MoS2 Vertical Heterostructures

Hongxiao Zhao,Yong Yan,Xiaohui Song,Aodi Dong,Jian Su,Huimin Jia 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.10

Constructing van der Waals (vdW) heterostructures with various-layered two-dimensional (2D) materials is attractive to design various materials and devices. For controllable fabrication of vdW heterostructures, it is very important to make the growth process clear. In this work, SnS2/MoS2 vertical heterostructures were synthesized by the one-step chemical vapor deposition (CVD) method. The bottom MoS2 triangle layers can be partially or completely covered by SnS2 layers. The interlayer charge separation was also observed in the heterostructures by photo-luminescence (PL) spectroscopy. The growth mechanism of SnS2/MoS2 vertical heterostructures was also discussed for the first time. MoS2 triangle layers form on the substrates at first and then grow a top layer of SnS2. This study will provide an important and practical method, as a guidance to prepare high-quality vertical heterostructures.

Advances in atomic layer deposited high-κ inorganic materials for gate dielectrics engineering of two-dimensional MoS2 field effect transistors

Zhang Ling,Xing Houying,Yang Meiqing,Dong Qizhi,Li Huimin,Liu Song 한국탄소학회 2022 Carbon Letters Vol.32 No.5

Molybdenum disulfide (MoS2) has been one of the most promising members of transition-metal dichalcogenides materials. Attributed to the excellent electrical performance and special physical properties, MoS2 has been broadly applied in semiconductor devices, such as field effect transistors (FETs). At present, the exploration of further improving the performance of MoS2-based FETs (such as increasing the carrier mobility and scaling) has encountered a bottleneck, and the application of high-κ gate dielectrics has become an effective approach to change this situation. Atomic layer deposition (ALD) enables high-quality integration of MoS2 and high-κ gate dielectrics at the atomic level. In this review, we summarize recent advances in the fabrication of two-dimensional MoS2 FETs using ALD high-κ materials as gate dielectrics. We first briefly discuss the research background of MoS2 FETs. Second, we expound the electrical and other essential properties of high-κ gate dielectrics, which are essential to the performance of MoS2 FETs. Finally, we focus on the advances in fabricating MoS2 FETs with ALD high-κ gate dielectrics on MoS2, as well as the optimized ALD processes. In addition, we also look forward to the development prospect of this field.

In Situ Assembly of Antifouling/Bacterial Silver Nanoparticle-Hydrogel Composites with Controlled Particle Release and Matrix Softening

Baek, Kwanghyun,Liang, Jing,Lim, Wan Ting,Zhao, Huimin,Kim, Dong Hyun,Kong, Hyunjoon American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.28

<P>Controlling bacterial contamination has been a major challenge for protecting human health and welfare. In this context, hydrogels loaded with silver nanoparticles have been used to prevent biofilm formation on substrates of interest. However, such gel composites are often plagued by rapid loss of silver nanoparticles and matrix softening, and thus the gel becomes less effective for antifouling. To this end, this study demonstrates that in situ photoreaction of an aqueous mixture of silver nitrates, poly(ethylene glycol) diacrylate, and vinylpyrrolidone results in a silver nanoparticle-laden hydrogel composite with minimal nanoparticle loss and matrix softening due to enhanced binding between nanoparticles and the gel. The resulting gel composite successfully inhibits the bacterial growth in media and the bacterial adhesion to surfaces of interest. We suggest that the results of this study serve to advance quality of materials with antifouling/bacterial activities.</P><P>An advanced, antifouling/bacterial hydrogel composite is structurally stable and sustainably sequesters encapsulated silver nanoparticles. The material can prevent biofilm formation on various plastic and metallic materials even with 10-fold lower silver content than that typically used in past studies.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-28/acsami.5b03313/production/images/medium/am-2015-033138_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b03313'>ACS Electronic Supporting Info</A></P>

Inhibition of miR-146a-5p and miR-8114 in Insulin-Secreting Cells Contributes to the Protection of Melatonin against Stearic Acid-Induced Cellular Senescence by Targeting Mafa

Shenghan Su,Qingrui Zhao,Lingfeng Dan,Yuqing Lin,Xuebei Li,Yunjin Zhang,Chunxiao Yang,Yimeng Dong,Xiaohan Li,Romano Regazzi,Changhao Sun,Xia Chu,Huimin Lu 대한내분비학회 2022 Endocrinology and metabolism Vol.37 No.6

Background: Chronic exposure to elevated levels of saturated fatty acids results in pancreatic β-cell senescence. However, targets and effective agents for preventing stearic acid-induced β-cell senescence are still lacking. Although melatonin administration can protect β-cells against lipotoxicity through anti-senescence processes, the precise underlying mechanisms still need to be explored. Therefore, we investigated the anti-senescence effect of melatonin on stearic acid-treated mouse β-cells and elucidated the possible role of microRNAs in this process. Methods: β-Cell senescence was identified by measuring the expression of senescence-related genes and senescence-associated β-galactosidase staining. Gain- and loss-of-function approaches were used to investigate the involvement of microRNAs in stearic acid-evoked β-cell senescence and dysfunction. Bioinformatics analyses and luciferase reporter activity assays were applied to predict the direct targets of microRNAs. Results: Long-term exposure to a high concentration of stearic acid-induced senescence and upregulated miR-146a-5p and miR-8114 expression in both mouse islets and β-TC6 cell lines. Melatonin effectively suppressed this process and reduced the levels of these two miRNAs. A remarkable reversibility of stearic acid-induced β-cell senescence and dysfunction was observed after silencing miR-146a-5p and miR-8114. Moreover, V-maf musculoaponeurotic fibrosarcoma oncogene homolog A (Mafa) was verified as a direct target of miR-146a-5p and miR-8114. Melatonin also significantly ameliorated senescence and dysfunction in miR-146a-5pand miR-8114-transfected β-cells. Conclusion: These data demonstrate that melatonin protects against stearic acid-induced β-cell senescence by inhibiting miR-146a-5p and miR-8114 and upregulating Mafa expression. This not only provides novel targets for preventing stearic acid-induced β-cell dysfunction, but also points to melatonin as a promising drug to combat type 2 diabetes progression.