http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Xiaodong Yu,Yanan Feng,Yan Zhao,Dianbin Huang,Jianhua Jiao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
Taking the hydrostatic support of the tiltable oil pad double rectangular cavity as the object, the fluid-thermal-solid coupling deformation analysis of the friction pair is carried out, and the three-dimensional morphology of the micro-gap oil film is obtained. An oil film thickness test device is built to verify the rationality of the numerical simulation method. It is found that the elastic deformations of rotational workbench and base under extreme loads are both concave deformations, the thermal deformations are both convex deformations, and the maximum thermal deformation is mainly concentrated on the outer oil sealing edge. The deformation of the downstream side oil sealing edge is higher than that of the reverse side oil sealing edge. The minimum oil film thickness is the minimum distance between the downstream side oil sealing edge and the lower surface of the hydrostatic guideway of the rotational workbench, where tribological failure is prone to occur.
Xiaodong Yu,Weicheng Gao,Yanan Feng,Guangqiang Shi,Shihao Li,Minmin Chen,Ruiming Zhang,Junfeng Wang,Wentao Jia,Jianhua Jiao,Ruichun Dai 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.6
Hydrostatic bearing has the advantages of wide speed range, large bearing capacity, high precision and stability. Hydrostatic-hydrodynamic hybrid bearing can make up for the lack of stiffness of hydrostatic bearing and prevent tribological failure under the condition of high speed and heavy load. Therefore, hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing have become important bearing parts of high-end computer numerical control (CNC) machine equipment. The research on hydrostatic and hydrostatic-hydrodynamic open a new way for precision improvement of high-end CNC machine equipment. This paper reviews research progress of hydrostatic linear guideway, hydrostatic rest and ram, hydrostatic thrust bearing, hydrostatic-hydrodynamic thrust bearing and hydrostatic-hydrodynamic spindle of high-end CNC machine equipment, and discusses the influence of structure and working parameters on lubrication performance, accuracy and stability of bearing parts. Finally, the future research direction in hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing are suggested. This review provides a theoretical basis for design and development of high-end CNC machine equipment in the future.
IL28B Is Associated with Outcomes of Chronic HBV Infection
Xiaodong Shi,Junqi Niu,Xiumei Chi,Yu Pan,Yanhang Gao,Wanyu Li,Chen Yang,Jin Zhong,Damo Xu,Manna Zhang,Gerald Minuk,Jing Jiang 연세대학교의과대학 2015 Yonsei medical journal Vol.56 No.3
Purpose: The role of IL28B gene variants and expression in hepatitis B virus (HBV) infections are not well understood. Here, we evaluated whether IL28B gene expression and rs12979860 variations are associated with HBV outcomes. Materialsand Methods: IL28B genetic variations (rs12979860) were genotyped by pyrosequencingof DNA samples from 137 individuals with chronic HBV infection [50 inactive carriers (IC), 34 chronic hepatitis B (CHB), 27 cirrhosis, 26 hepatocellular carcinoma (HCC)], and 19 healthy controls. IL28A/B mRNA expression in peripheralblood mononuclear cells was determined by qRT-PCR, and serum IL28B proteinwas measured by ELISA. Results: Patients with IL28B C/C genotype had greater IL28A/B mRNA expression and higher IL28B protein levels than C/T patients. Within the various disease stages, compared to IC and healthy controls, IL28B expression was reduced in the CHB, cirrhosis, and HCC cohorts (CHB vs. IC, p=0.02; cirrhosis vs. IC, p=0.01; HCC vs. IC, p=0.001; CHB vs. controls, p<0.01; cirrhosis vs. controls, p<0.01; HCC vs. controls, p<0.01). When stratified with respect to serum HBV markers in the IC and CHB cohorts, IL28B mRNA and protein levels were higher in HBeAg-positive than negative individuals (p=0.01). Logistic regression analysis revealed that factors associated with high IL28B proteinlevels were C/C versus C/T genotype [p=0.016, odds ratio (OR)=0.25, 95% confidence interval (CI)=0.08‒0.78], high alanine aminotransferase values (p<0.001, OR=8.02, 95% CI=2.64‒24.4), and the IC stage of HBV infection (p<0.001). Conclusion: Our data suggest that IL28B genetic variations may play an important role in long-term development of disease in chronic HBV infections.
A Control Method to Make LQR Robust: A Planes Cluster Approaching Mode
Xiaodong Liu,Yunjie Wu,Yu Zhang,Song Xiao 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.2
Linear quadratic regulator (LQR) is an optimal controller being used for linear systems, and it can minimize the comprehensive quadratic performance index (QPI) with respect to convergence error and control consumption. However, LQR lacks the robust property to cope with parameter perturbations and external disturbances. Aiming at the above deficiency of LQR, a robust LQR (RLQR) is proposed for linear systems under the guideline of planes cluster approaching mode (PCAM). In the proposed RLQR, one nonlinear item is introduced into control law, and it cooperates with the other linear item to guarantee the global asymptotic stability in the presence of equivalent disturbances. The conditions of global asymptotic stability are deduced by the method of Lyapunov function. Simulation results present that, the chosen LTI plant using RLQR possesses smaller QPI in the existence of time-varying disturbances, compared with the conventional LQR and sliding mode controller (SMC).
China Urban Economic Reform and Development in the Past 30 Years
Xiaodong Fu,Jing Yu,Yaohui Li 서울시립대학교 도시과학연구원 2009 도시과학국제저널 Vol.13 No.2
It has been already 30 years since China began her reforms and opened to the outside world. During these recent 30 years, China’s urban economy has not only gained rapid expansion on a total quantity scale, but has also made qualitative leaps and remarkable upgrades in economic system and operational mechanism. This paper studies transitional process of urban economic reform as well as step-by-step liberation of urban economic elements during the recent 30 years in order to explore the new mode of China’s urban economic development. Based on the relevant statistical data of China’s urban economy and the corresponding institutional analysis, it presents that China’s urban economic system has gradually shifted from planned allocation to a more open market, that the utilization of urban function has changed from monomer to urban group, that the measure of urban economic level has transformed from simple output to the whole urban value, that the new impetus of urban economic development has shifted to urban management, that urban development concept and guidance has broken through the former size limitation.
Position-pose Control of a Pneumatic 3-UPU Robot Based on Immersion and Invariance
Yu Liu,Xiaodong Wang,Guoxin Zhao,Shuchao Ma 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3
For pneumatic servo systems, the piston movement, time-varying parameters, and modeling uncertainties make high-precision position control difficult. A third-order mathematical model was established for a pneumatic 3-UPU (universal-prismatic-universal) robot system to provide a roughly accurate reference model for the control algorithm. Subsequently, a high-precision position-pose control algorithm based on immersion and invariance (I&I) was developed, where the leakage flow in the cylinder was incorporated as an interference term in the state equation, and the state equation was expanded. In addition, through a reasonable design of the compensation function and adaptive rate, the invariance and attraction of the error flow pattern were realized. The disturbance error was estimated in real time based on the adaptive law. Through the sliding surface, the control rate was designed, and the position-pose control of the robot was realized. The results showed that the I&I controller exhibits a strong robustness with a steady-state control accuracy of approximately 0.3 mm and a dynamic (0.2 Hz) tracking mean-squared error less than 6.4 mm.
Achieving Maximal NJRL Method for Jamming UAVs Network
Zhang Yu,Peng Xiaodong,Liu Feng 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.2
Different from others, we focus on designing jamming methods for disrupting UAVs network efficiently. The jamming problem is formulated. Then we introduce two new methods (AMN-U2C and AMN-U2U) for jamming UAVs network. Both of them adopt the idea intending to achieve maximal number of jammed receiving links. AMN-U2C method searches locations for jammer by moving jammers along the path from the point of a UAV to the center point of others. AMN-U2U method searches by shifting jammers from the point of a UAV to another UAV. Finally we simulate the jamming attack on UAVs network using AMN-U2C, AMN-U2U, TP, GA and Random methods. The result shows AMN-U2U does best at most cases.
Online Hot Topic Detection Based on Segmented Timeline and Aging Theory
Ruiguo Yu,Xiaodong Xie,Yongxing Li,Mankun Zhao,Xuyuan Dong,Muwen He,Peng Chang,Zan Wang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.2
With a great deal of digitized textual information now available on the internet, it is almost impossible for people to assimilate all the information timely. Therefore, the technologies of topic detection and tracking are used for constructing news topics from news stories in order to bring convenience to people. However, traditional topic detection methods are not always so effective in detecting emerging hot news topics in a short period of time, and most topic detection methods use single-pass clustering algorithm which is with low accuracy and very sensitive to the input sequence of news documents. In order to improve clustering accuracy, we utilize a temporal distance factor to segment timeline into equal parts and propose a novel two-times single-pass clustering algorithm to deal with news stories in each part of timeline separately. Moreover, the aging theory is combined with our approach to build life-span model of topics from which we can obtain variation trend of hotness value of topics. The results of experiments show that our approach is effective and the life circle model of topics established by our method can conform to reality well.