Research for the bearing fit effect on the vibration characteristics of spindle rotor-bearing system

Zhan Wang,Siyang Chen,Wenzhi He,Zinan Wang,Zhongxian Xia 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

Spindle bearing fits mainly include interference fit of inner ring and clearance fit of outer ring, which directly affect the vibration characteristics of spindle rotor-bearing system. In this paper, the influence of spindle bearing inner and outer ring fits on bearing support stiffness is firstly studied. Considering the spindle bearing inner and outer ring fits, a dynamic model of spindle rotor-bearing system is established. Then, the analysis methods of bifurcation and time domain are used to perform simulation analysis. The influence of bearing fit on the vibration characteristics of rotor system is researched. Lastly, at different rotating speeds, bearing fits experiments are conducted on built motorized spindle test platform, which verifies the correctness of the dynamic model. The results show that the influence of bearing fit on vibration is nonlinear. The influence of clearance fit on vibration is smaller, when the clearance fit value of bearing outer ring is about 4-6 μm. The vibration characteristics of rotor are more sensitive to the clearance fit of bearing outer ring than the interference fit of bearing inner ring. The research work provides an important theoretical basis for the optimal of spindle bearing assembly.

Partial Discharge Detection Method Based on DD-DT CWT and Singular Value Decomposition

Wu Chao,Gao Yiran,Wang Ruoyan,Wang Kai,Liu Siyang,Nie Yongjie,Wang Ping 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

Partial discharge (PD) detection is signifi cant for insulation condition evaluation of electrical equipment. However, it often happens that the PD signals are submerged by interferences, which will cause the inaccurate detection results. In this paper, we propose a PD detection method based on double-density dual-tree complex wavelet transform (DD-DT CWT) and singular value decomposition (SVD) to solve this problem. The denoising method based on DD-DT CWT has better performance in both removing interferences and retaining features of PD signals. The inner product of the singular value matrix obtained by applying SVD to denoised high-frequency wavelet coeffi cient matrix can concisely represent the complexity of the tested signal, which can be used as a basis to judge the existence of the PD signal. Besides, Otsu algorithm is introduced to calculate the threshold to locate the appearance time of the PD signal. Experimental results show that the proposed method can detect the PD signal with the accuracy rate of 77.8% when PD signals are submerged by noises, while the traditional method cannot detect the existence of the PD signal. In addition, only the method proposed in this paper can detect the appearance time of the PD signal with the accuracy rate of 97.2%.

An Approach Integrating Dimensional Analysis and Field Data for Predicting the Load on Tunneling Machine

Siyang Zhou,Yilan Kang,Haimei Xie,Lihui Wang,Qian Zhang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.7

The forecast of machine performance has been widely discussed in recent years, where accurate predictions with common regularity could reduce costs and achieve time-efficient construction. This study uses the case of predicting the load (including the thrust and torque) acting on tunneling machine. Because most data-mining techniques are black-box models, which rely too much on specific data and cannot reveal the mechanics principle. A new approach is developed to deal with this problem, which combines data analysis with mechanics principle through dimensional analysis. Firstly, power relations between the soil properties, operational, structural parameters and the load are obtained. Then dimensionless model is established, which involves the dominant dimensionless groups representing operating status and geological conditions. At last, to overcome the problem of high correlation between independent variables, ridge estimation is performed. The obtained dimensionless model is in accordance with Krause Empirical Model for the power relationship between the load and the cutterhead diameter. Moreover, the earth pressure in the chamber is proportional to the load, which is consistent with previous experimental results. In addition to its prediction ability, the validation data from two urban subway projects show that, the proposed model can correctly indicating the geological variation during excavation.

Prediction of dryout-type CHF for rod bundle in natural circulation loop under motion condition

Huang, Siyang,Tian, Wenxi,Wang, Xiaoyang,Chen, Ronghua,Yue, Nina,Xi, Mengmeng,Su, G.H.,Qiu, Suizheng Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4

In nuclear engineering, the occurrence of critical heat flux (CHF) is complicated for rod bundle, and it is much more difficult to predict the CHF when it is in natural circulation under motion condition. In this paper, the dryout-type CHF is investigated for the rod bundle in a natural circulation loop under rolling motion condition based on the coupled analysis of subchannel method, a one-dimensional system analysis method and a CHF mechanism model, namely the three-fluid model for annular flow. In order to consider the rolling effect of the natural circulation loop, the subchannel model is connected to the one-dimensional system code at the inlet and outlet of the rod bundle. The subchannel analysis provides the local thermal hydraulic parameters as input for the CHF mechanism model to calculate the occurrence of CHF. The rolling motion is modeled by additional motion forces in the momentum equation. First, the calculation methods of the natural circulation and CHF are validated by a published natural circulation experiment data and a CHF empirical correlation, respectively. Then, the CHF of the rod bundle in a natural circulation loop under both the stationary and rolling motion condition is predicted and analyzed. According to the calculation results, CHF under stationary condition is smaller than that under rolling motion condition. Besides, the CHF decreases with the increase of the rolling period and angular acceleration amplitude within the range of inlet subcooling and mass flux adopted in the current research. This paper can provide useful information for the prediction of CHF in natural circulation under motion condition, which is important for the nuclear reactor design improvement and safety analysis.

Honokiol ameliorates endothelial dysfunction through suppression of PTX3 expression, a key mediator of IKK/IκB/NF-κB, in atherosclerotic cell model

Ling Qiu,Rong Xu,Siyang Wang,Shuijun Li,Hongguang Sheng,Jiaxi Wu,Yi Qu 생화학분자생물학회 2015 Experimental and molecular medicine Vol.47 No.-

Pentraxin 3 (PTX3) was identified as a marker of the inflammatory response and overexpressed in various tissues and cells related to cardiovascular disease. Honokiol, an active component isolated from the Chinese medicinal herb Magnolia officinalis, was shown to have a variety of pharmacological activities. In the present study, we aimed to investigate the effects of honokiol on palmitic acid (PA)-induced dysfunction of human umbilical vein endothelial cells (HUVECs) and to elucidate potential regulatory mechanisms in this atherosclerotic cell model. Our results showed that PA significantly accelerated the expression of PTX3 in HUVECs through the IκB kinase (IKK)/IκB/nuclear factor-κB (NF-κB) pathway, reduced cell viability, induced cell apoptosis and triggered the inflammatory response. Knockdown of PTX3 supported cell growth and prevented apoptosis by blocking PA-inducted nitric oxide (NO) overproduction. Honokiol significantly suppressed the overexpression of PTX3 in PA-inducted HUVECs by inhibiting IκB phosphorylation and the expression of two NF-κB subunits (p50 and p65) in the IKK/IκB/NF-κB signaling pathway. Furthermore, honokiol reduced endothelial cell injury and apoptosis by regulating the expression of inducible NO synthase and endothelial NO synthase, as well as the generation of NO. Honokiol showed an antiinflammatory effect in PA-inducted HUVECs by significantly inhibiting the generation of interleukin-6 (IL-6), IL-8 and monocyte chemoattractant protein-1. In summary, honokiol repaired endothelial dysfunction by suppressing PTX3 overexpression in an atherosclerotic cell model. PTX3 may be a potential therapeutic target for atherosclerosis.

Important Role of Immunological Responses to Environmental Exposure in the Development of Allergic Asthma

Xinliu Lin,Xia Ren,Xiaojun Xiao,Zhaowei Yang,Siyang Yao,Gary WK Wong,Zhigang Liu,Charles Wang,Zhong Su,Jing Li 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.6

Allergic asthma is a public health problem that affects human health and socioeconomic development. Studies have found that the prevalence of asthma has significantly increased in recent years, which has become particularly pronounced in developed countries. With rapid urbanization in China in the last 3 decades, the prevalence of asthma has increased significantly in urban areas. As changes in genetic backgrounds of human populations are limited, environmental exposure may be a major factor that is responsible for the increased prevalence of asthma. This review focuses on environmental components of farms and rural areas that may have protective effects in reducing the development of asthma. Farm and rural related microorganism- and pathogen-associated molecular patterns are considered to be important environmental factors that modulate host's innate and adaptive immune system to induce protection effects later in life. Environmental microbial-related immunotherapy will also be discussed as the future research direction for the prevention of allergic asthma.