Characterizing wafer stage transmission errors via binary decision diagram and dynamic fault tree

Junyu Guo,Guo-Zhong Fu,Hong-Zhong Huang,Yu Liu,Yanfeng Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.11

The wafer stage, as a key subsystem of the dual-stage lithographic tool, possesses the characteristic of high moving accuracy. The fault tree analysis (FTA), which plays an important role in the design stage of the wafer stage, is performed to distinguish the critical events leading to the overall transmission error. However, in view of the complexity of the wafer stage’s structure and operation mechanism, the binary decision diagrams and dynamic fault tree analysis methods are implemented in this paper to obtain a simplified calculation process and a supplement with the dynamic characteristic respectively. This is not achieved by the traditional FTA method. The event “wafer stage’s repetitive error along X axis exceeds 5 nm” is viewed as the top event of the fault tree. In this paper, we identify the critical factors affecting the kinematic accuracy of the wafer stage.

Bayesian degradation assessment of CNC machine tools considering unit non-homogeneity

Junyu Guo,Yanfeng Li,Bo Zheng,Hong-Zhong Huang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

Field reliability assessment and prediction is critical for the estimation, operation and health management of CNC machine tools. The classical methods for field reliability of CNC Machine Tools assessment and prediction are challenged with the issues of expensive reliability tests, small sample size and unit non-homogeneity. In order to solve these problems, this paper introduces a degradation analysis based reliability assessment method for CNC machine tools under performance testing. Since the degradation is an independent increment process, the gamma process is employed to characterize the degradation process of CNC machine tools. The random effects are introduced to accommodate performance degradation model with unit non-homogeneity. The parameters of model are updated by Bayesian estimation approach. As a case study, the CNC Machine Tools is studied to illustrate the approach. And the proposed method is demonstrated precise for practical use.

circLETM1 upregulates KRT80 via adsorbing miR-143-3p and promotes the progression of colorectal cancer

Li Hua,Guo Junyu,Qin Zhongwei,Wei Mingwei,Guo Houji,Huang Fuda 대한독성 유전단백체 학회 2023 Molecular & cellular toxicology Vol.19 No.3

Background Emerging evidence has indicated that circular RNAs (circRNAs) play vital roles in colorectal cancer (CRC). CircRNA leucine zipper and EF-hand containing transmembrane protein 1 (circLETM1) have been found to be ectopic in CRC, but their role in CRC has not been studied yet. Objective This study aims to explore the roles of circLETM1 in CRC and the possible molecular mechanism. Result The results showed that circLETM1 was highly expressed in CRC cells, and was localized at the cytoplasm. Functional assays verifi ed that overexpression of circLETM1 could facilitate, but circLETM1 downregulation could hamper proliferation, migration and invasion abilities of CRC cells. In addition, mechanism assays found that circLETM1 absorbed and reduced microRNA (miR)-143-3p expression to promote keratin 80 (KRT80). Rescue experiments proved that circLETM1 mediated CRC proliferation, migration and invasion through KRT80. Conclusion Taken together, our results suggested that circLETM1 promotes proliferation, migration and invasion through the miR-143-3p/KRT80 axis in CRC. Therefore, targeting circLETM1 may provide a novel option for CRC treatment.

Characteristics of isolated lactic acid bacteria and their effects on the silage quality

Siran Wang,Xianjun Yuan,Zhihao Dong,Junfeng Li,Gang Guo,Yunfeng Bai,Junyu Zhang,Tao Shao 아세아·태평양축산학회 2017 Animal Bioscience Vol.30 No.6

Objective: Four lactic acid bacteria (LAB) strains isolated from common vetch, tall fescue and perennial ryegrass on the Tibetan Plateau were characterized, and their effects on the fermentation quality of Italian ryegrass (Lolium multiflorum Lam.) silage were studied. Methods: The four isolated strains and one commercial inoculant (G, Lactobacillus plantarum MTD-1) were evaluated using the acid production ability test, morphological observation, Gram staining, physiological, biochemical and acid tolerance tests. The five LAB strains were added to Italian ryegrass for ensiling at three different temperatures (10°C, 15°C, and 25°C). Results: All isolated strains (LCG3, LTG7, I5, and LI3) could grow at 5°C to 20°C, pH 3.0 to 8.0 and NaCl (3.0%, 6.5%). Strains LCG3, LTG7, I5, and LI3 were identified as Lactobacillus plantarum, Pediococcus acidilactici, Lactobacillus paraplantarum, and Lactobacillus casei by sequencing 16S rDNA, respectively. All LAB inoculants significantly (p<0.05) increased lactic acid (LA) contents and ratios of lactic acid to acetic acid, and reduced pH and ammonia nitrogen/ total nitrogen (AN/TN) compared with uninoculated silages at various temperatures (10°C, 15°C, and 25°C). Compared to the commercial inoculant G, I5, and LI3 showed similar effects on improving the silage quality of Italian ryegrass at 10°C and 15°C, indicated by similar pH, LA content and AN/TN. Conclusion: All inoculants could improve the silage fermentation quality at various temperatures (10°C, 15°C, and 25°C). At the temperature of 10°C and 15°C, strain I5 and LI3 had similar effects with the commercial inoculant G on improving the silage quality of Italian ryegrass.

Remaining useful life prediction of planet bearings based on conditional deep recurrent generative adversarial network and action discovery

Jun Yu,Zhenyu Guo 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1

Planet bearing vibration signals are complex and non-stationary owing to the time-varying vibration transmission path from fault point to accelerometers. In addition, due to the influence of speed and load variation, planetary gearboxes often operate under varying conditions, which causes the acquired vibration signals to be nonlinear. These seriously degrade the performance of the RUL prediction methods. Moreover, there are only few training samples for the RUL prediction of planet bearings. To address these problems, an RUL prediction method of planet bearings using conditional deep recurrent generative adversarial network (C-DRGAN) and action discovery (AD) is presented. First, gated recurrent unit neural network is integrated with conditional generative adversarial network to construct the C-DRGAN, which extracts fault features from nonlinear and non-stationary signals so as to realize the RUL prediction of planet bearings under small samples and varying conditions. Then, the training algorithm based on AD is employed to train the C-DRGAN to enhance convergence speed and reduce training time. Finally, a multiple linear regression classifier is utilized to predict the RUL of planet bearings. The performance of the presented method is validated through an accelerated fatigue life experiment of planet bearings. Experimental analyses demonstrate that this method possesses strong processing adaptability to nonlinear and non-stationary signals and obtains excellent performance under small samples.

Conversion of syngas to C2+ oxygenates over Rh-based/SiO2 catalyst: The promoting effect of Fe

Jun Yu,Dongsen Mao,Lupeng Han,Qiangsheng Guo,Guanzhong Lu 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.3

The effect of Fe promoter on the catalytic properties of Rh–Mn–Li/SiO2 catalyst for CO hydrogenation was investigated. The catalysts were comprehensively characterized by means of X-ray diffraction (XRD), N2adsorption–desorption, temperature programmed reduction (TPR), temperature programmed desorption (TPD), temperature programmed surface reaction (TPSR), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Activity testing results showed that low loading of Fe (≤0.1 wt%)improved the reactivity and yield of C2+ oxygenates; however, the opposite effect appeared at the high values of Fe (>0.1 wt%). Characterization results suggested that the addition of Fe strengthened the Rh–Mn interaction and increased the desorption/transformation rate of adsorbed CO, which could be responsible for the increase of CO conversion. But on the other hand, the existence of Fe might deposit over the Rh surface, and decreased the number of active sites, resulting in the decrease of CO conversion when the Fe amount was excessive. The selectivity to C2+ oxygenates varied inversely with the reducibility of Rh oxide species. Moreover, it is proposed that the transformation of dicarbonyl Rh+(CO)2into H–Rh–CO is favorable for the formation of C2+ oxygenates, and the hydrogenation ability of Fe can increase the hydrogenation of acetaldehyde to ethanol.

Research on the Axial Magnetic Levitation Force Acting on the Ring Magnet Suspended in Magnetic Fluid : Considering a Radial Eccentricity

Jun Yu,Decai Li,Nannan Di,Ningning Guo 한국자기학회 2019 Journal of Magnetics Vol.24 No.2

The self-suspension of magnet in magnetic fluid has been widely used in micromechanical systems, sensors, and dampers. The magnetic field associated with the ring magnet is obtained by numerical calculation and simulation through which the axial magnetic levitation force is calculated, and the numerical calculation, simulation, and experimental results agree with each other. The influence of the radial eccentricity of the ring magnet on the axial magnetic levitation force is studied, the ring magnet will experience a maximum axial magnetic levitation force without radial eccentricity. With the increase of radial eccentricity and the decrease of the distance between the bottom of the ring magnet and container, the axial magnetic levitation force will continue to decrease. But it is worth noting that the magnitude of the change caused by radial eccentricity is negligible compared to that of the axial magnetic levitation force.