Synchronous characteristic of three homodromy motors in vibrating isolation system

Yongjun Hou,Huan Peng,Pan Fang,Min Zou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1

This paper researched the synchronous characteristic of three homodromy motors in a secondary isolation system. Firstly, the motion differential equations of the system were established via employing Lagrange’s equation. The Laplace transform was used to deduce approximate solutions of displacement. Next, the ability of vibrating isolation was determined through amplitude ratio. Secondly, the synchronous condition and steady criterion was obtained via employing the average small parameters method and Lyapunov criterion. And then the influence of structural parameters of the system on synchronous ability was analyzed. Moreover, the synchronous characteristics of the system, including the difference of residual torque among induction motors, the synchronous ability, the output torque of motors and the stable phase difference, were discussed through numerical analyses. Finally, the accuracy of theoretical analyses was proved through computer simulation results. It is shown that, the ability of vibrating isolation is principally impacted by vertical spring stiffness; the greater the installation distance among three motors, the easier to achieve synchronous motion of the rotors;meanwhile, the output torque of asynchronous motors is affected by the synchronous state of the vibrating system; the synchronous characteristic is mainly affected by the mounting dip angle of motors and the installation distance among motors. The research results can promote development of vibration engineering and related fields.

Study on stability of self-synchronous far-resonant vibrating system of two eccentric rotors considering material impact

Yongjun Hou,Guang Xiong,Pan Fang,Yuwen Wang,Mingjun Du 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

The self-synchronizing far-resonant vibrating system of two eccentric rotors is widely used in petroleum, mining and food industries, and its motion stability is affected by material impact. However, the synchronous characteristics and stability of this kind of the system are studied rarely. Based on the background, a simplified mechanical model of the selfsynchronous vibrating system driven by two eccentric rotors considering material impact is proposed. Firstly, the differential equations of motion about the system in non-collision and collision phase are established by using Lagrange equation and the theorem of momentum. Then, the section of Poincare maps and linearization matrix at the fixed point are solved. Finally, the dynamic behavior of material and system is analyzed, and then the change characteristics of the phase difference of the two eccentric rotors are revealed by numerical simulation. It can be concluded that the motion forms of the system and the rules of abrupt change about the phase difference evolve from periodic variation into chaotic state with the mass ratio of material to vibrating body increasing.

Adsorption differences and mechanism of chitooligosaccharides with specific degree of polymerization on macroporous resins with different functional groups

Yanying Hou,Lujie Liu,Xingxing Zhang,Yuechao Zhu,Yongjun Qiu,Liming Zhao 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-

Ion exchange resins are promising materials for separating chitooligosaccharides (COSs) with differentdegrees of polymerization (DP). The adsorbent functional groups significantly determine the interactionswith COSs and affect their adsorption and separation efficiency. This study investigated the adsorptionbehaviors of COSs on macroporous cation exchange resins with different functional groups to clarifythe functional group effect on the adsorption of COSs with different DP, which can also help to providea theoretical basis for the selection of separation medium and optimization of the separation technicsof COSs. The results showed that the adsorption of COSs on sulfonic-acid type resin DX-10 andcarboxylic-acid type resin DC-10 were favorable, and the adsorption isotherms were in accord withthe Sips model. Adsorption thermodynamics showed that temperature had opposite effects on the tworesins’ equilibrium adsorption capacity of COSs. The diffusion coefficient of COSs on DX-10 resin wasgreater, and the affinity gap between COSs on DX-10 resin was larger than that of DC-10 resin, whichis beneficial for improving the separation resolution of COSs. In contrast, the interaction energy betweenCOSs with high DP and DC-10 resin was weaker compared with DX-10, which made the elution of COSswith high DP easier.

Collateral Flow in Magnetic Resonance Angiography: Prognostic Value for Vertebrobasilar Stenosis With Stroke Recurrence

Long Yan,Ying Yu,Kaijiang Kang,Zhikai Hou,Min Wan,Weilun Fu,Rongrong Cui,Yongjun Wang,Zhongrong Miao,Xin Lou,Ning Ma 대한신경과학회 2022 Journal of Clinical Neurology Vol.18 No.5

Background and Purpose Intracranial vertebrobasilar atherosclerotic stenosis (IVBAS) is a major cause of posterior circulation stroke. Some patients suffer from stroke recurrence despite receiving medical treatment. This study aimed to determine the prognostic value of a new score for the posterior communicating artery and the P1 segment of the posterior cerebral artery (PCoA-P1) for predicting stroke recurrence in IVBAS. Methods We retrospectively enrolled patients with severe IVBAS (70%–99%). According to the number of stroke recurrences, patients were divided into no-recurrence, single-recurrence, and multiple-recurrences groups. We developed a new 5-point grading scale, with the PCoA-P1 score ranging from 0 to 4 based on magnetic resonance angiography, in which primary collaterals were dichotomized into good (2–4 points) and poor (0 or 1 point). Stroke recurrences after the index stroke were recorded. Patients who did not experience stroke recurrence were compared with those who experienced single or multiple stroke recurrences. Results From January 2012 to December 2019, 176 patients were enrolled, of which 116 (65.9%) had no stroke recurrence, 35 (19.9%) had a single stroke recurrence, and 25 (14.2%) had multiple stroke recurrences. Patients with single stroke recurrence (odds ratio [OR]= 4.134, 95% confidence interval [CI]=1.822–9.380, p=0.001) and multiple stroke recurrences (OR=6.894, 95% CI=2.489–19.092, p<0.001) were more likely to have poor primary collaterals than those with no stroke recurrence. Conclusions The new PCoA-P1 score appears to provide improve predictions of stroke recurrence in patients with IVBAS

Computational and experimental characterization of estrogenic activities of 20(S, R)-protopanaxadiol and 20(S, R)-protopanaxatriol

Tiehua Zhang,Shuning Zhong,Ligang Hou,Yongjun Wang,XiaoJia Xing,Tianzhu Guan,Jie Zhang,Tiezhu Li 고려인삼학회 2020 Journal of Ginseng Research Vol.44 No.5

Background: As the main metabolites of ginsenosides, 20(S, R)-protopanaxadiol [PPD(S, R)] and 20(S, R)-protopanaxatriol [PPT(S, R)] are the structural basis response to a series of pharmacological effects of their parent components. Although the estrogenicity of several ginsenosides has been confirmed, however, the underlying mechanisms of their estrogenic effects are still largely unclear. In this work, PPD(S, R) and PPT(S, R) were assessed for their ability to bind and activate human estrogen receptor α(hERα) by a combination of in vitro and in silico analysis. Methods: The recombinant hERα ligand-binding domain (hERa-LBD) was expressed in E. coli strain. The direct binding interactions of ginsenosides with hERα-LBD and their ERα agonistic potency were investigated by fluorescence polarization and reporter gene assays, respectively. Then, molecular dynamics simulations were carried out to simulate the binding modes between ginsenosides and hERα-LBD to reveal the structural basis for their agonist activities toward receptor. Results: Fluorescence polarization assay revealed that PPD(S, R) and PPT(S, R) could bind to hERα-LBD with moderate affinities. In the dual luciferase reporter assay using transiently transfected MCF-7 cells, PPD(S, R) and PPT(S, R) acted as agonists of hERα. Molecular docking results showed that these ginsenosides adopted an agonist conformation in the flexible hydrophobic ligand-binding pocket. The stereostructure of C-20 hydroxyl group and the presence of C-6 hydroxyl group exerted significant influence on the hydrogen bond network and steric hindrance, respectively. Conclusion: This work may provide insight into the chemical and pharmacological screening of novel therapeutic agents from ginsenosides.

Study on synchronization characteristics for self-synchronous vibration system with dual-frequency and dual-motor excitation

Min Zou,Pan Fang,Huan Peng,Duyu Hou,Mingjun Du,Yongjun Hou 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In petroleum drilling engineering, drilling shakers are critical devices for cleansing solid particles and recycling drilling fluid. For the problem that the vibration screen with a single frequency usually results in flurry overflow due to the blocking of screen mesh, a selfsynchronous vibratory system with dual-frequency and dual-motor excitation is proposed. But it is not clear about the synchronization mechanism and dynamic characteristics of the system, which causes a lack of theoretical description for the source of synchronization phenomenon. Hence, this paper explores the synchronization mechanism and dynamic characteristics around the proposed system above. First, vibration and stability theory are employed to master the dynamic characteristics of the system, and the dynamic model is established by Lagrange equation. Then, displacement responses of the system are obtained by dimensionless formulas. Synchronous condition and synchronous stability between the unbalanced rotors are derived with small parameter method and Poincare method. Finally, some computer simulations are implemented to further verify the correctness of the theoretical analysis. The research result shows that the synchronous ability between the two unbalanced rotors actuated by dual-frequency excitation is related to the distance from the rotating center of the motor to the centroid of supporting body, and the greater the distance value, the better the synchronization of the vibrating system. This study will promote the recycle technology development of drilling fluid and settlement of the common scientific issues in vibrating synchronization.