Thermal-mechanical coupling analysis and experimental study on CNC machine tool feed mechanism

Shihao Liu,Mao Lin 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.6

As the CNC machine tool feed mechanism is affected by joint action of heat and load during the working process, thermal–mechanical coupling analysis and experimental research on CNC machine tool feed mechanism are conducted. On the basis of exploring the thermal–mechanical coupling effect of CNC machine tool feed mechanism, a thermal–mechanical coupling dynamic analysis method is proposed through combining multi-step finite element simulation with temperature field experiment.According to the proposed method, the transient and steady-state simulation analysis on CNC machine tool feed mechanism are conducted and conclusions obtained are as follows, before the whole feed mechanism reaches thermal balance state, the thermal–mechanical coupling effect makes the deformation of the feed mechanism increase with the temperature rising. The correctness of the proposed thermal–mechanical coupling dynamic analysis method was verified by the contrastive analysis of the experiments. Therefore, in the process of CNC machine tool feed mechanism’s analysis and design, the influence of thermal–mechanical coupling effect on dynamic performance should be considered.

Angle-stable top-emitting white organic light-emitting devices employing a down-conversion layer

Shihao Liu,Xuemei Wen,Wenbo Liu,Wei Zhang,Jing-Yuan Wang,Wenfa Xie,Letian Zhang 한국물리학회 2014 Current Applied Physics Vol.14 No.11

Angle-stable white top-emitting organic light-emitting devices (WTEOLEDs) by the combination of a blue TEOLED with a down-conversion (DC) layer are demonstrated. The DC layer is composed of red fluorescent dye doped in a host of tris (8-hydroxy-quinolinato) aluminum. The TEWOLED shows a CIE coordinates of (0.240, 0.332) and a maximum current efficiency of 3.95 cd/A. Furthermore, theWTEOLED shows excellently angle-stable characteristic, the CIE coordinates at 20 mA/cm2 only shift by (0.023, 0.007) from 0 to 60. It can be attributed to the angle-stable blue TEOLED based on the Ag/Ge/Ag transparent cathode.

Land Surface Temperature Retrieval from the Medium Resolution Spectral Imager Thermal Data

Hailei Liu,Shenglan Zhang,Shihao Tang 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.1

A single channel land surface temperature (LST) retrieval algorithm named Single Channel Water Vapor Dependent (SCWVD) method was presented for Medium Resolution Spectral Imager (MERSI) thermal infrared band aboard FengYun-3A (FY-3A) satellite. Water Vapor Content (WVC) is the only input parameter in the algorithm assuming the surface emissivity is known. NCEP reanalysis monthly mean datasets were used to develop the SCWVD algorithm. Some tests, including global numerical simulations and validations with both in-situ measurements and MODIS LST product at Lake Tahoe, USA, were carried out to evaluate the algorithm performance. The simulation results showed that the LST could be estimated by the SCWVD algorithm with the root mean square error (RMSE) less than 0.8 K. In the inversion test, MERSI Level 2 water vapor product was employed, and the MERSI band emissivity was calculated using the MODIS band 31 and 32 emissivity by an empirical expression. The results show that the difference between the retrieved MERSI LST and the in-situ measurements is less than 1 K in most situations. The comparison with the MODIS LST products (V5) shows that the RMSE is about 2.3 K.

Numerical investigation of the critical heat fl ux in a 5 × 5 rod bundle with multi-grid

Wei Liu,Zemin Shang,Shihao Yang,Lixin Yang,Zihao Tian,Yu Liu,Xi Chen,Qian Peng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5

To improve the heat transfer efficiency of the reactor fuel assembly, it is necessary to accurately calculatethe two-phase flow boiling characteristics and the critical heat flux (CHF) in the fuel assembly. In thispaper, a Eulerian two-fluid model combined with the extended wall boiling model was used tonumerically simulate the 5 5 fuel rod bundle with spacer grids (four sets of mixing vane grids and foursets of simple support grids without mixing vanes). We calculated and analyzed 11 experimental conditions under different pressure, inlet temperature, and mass flux. After comparing the CHF and thelocation of departure from the nucleate boiling obtained by the numerical simulation with the experimental results, we confirmed the reliability of computational fluid dynamic analysis for the prediction ofthe CHF of the rod bundle and the boiling characteristics of the two-phase flow. Subsequently, weanalyzed the influence of the spacer grid and mixing vanes on the void fraction, liquid temperature, andsecondary flow distribution. The research in this article provides theoretical support for the design of fuelassemblies

Distribution characteristic of hydrodynamic pressure in the ballastless track crack under the train load

Shihao Cao,Rongshan Yang,Luhui Shi,Jiali Li,Xueyi Liu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2

In the areas which have rich rain and poor drainage, there may be obvious water damage existed in the interlamination of ballastless track. The damage is mainly caused by repeated hydraulic fracturing. Aimed at this problem, the calculation model of water pressure under the train load was established on the basis of fluid-structure interaction theory, and the influence of crack geometry and train operation condition on water pressure were analyzed. The results show that, when the train is close to and far away from the location of the crack, the water pressure changes periodically under the train load, and the pressure peak occurs at the crack front. Simultaneously, the positive and negative pressure may both exist in the crack. The crack geometry affects the distribution of water pressure significantly, the value of water pressure is inversely proportional to the vertical opening of crack, and proportional to the cubic polynomial of horizontal crack depth. The water pressure increases firstly with the increase of longitudinal crack length, then decreases gradually and tends to be stable finally. The train operation condition is also an important factor affecting the distribution of water pressure, the value of water pressure is linear with the axle load, and proportional to the square of train speed. These research results will provide a hydraulic boundary condition for further study of water damage mechanism.

Toward Understanding the Adsorption And Inhibition Mechanism of Cu‑MBTA Passivation Film on Copper Surface: A Combined Experimental and DFT Investigation

Mengrui Liu,Da Yin,Baimei Tan,Fan Yang,Xiaoqin Sun,Pengcheng Gao,Shihao Zhang,Yazhen Wang 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.1

The adsorption and passivation reactions of 5-methyl benzotriazole (MBTA) with different copper samples (as received, citricacid treated and citric acid and KIO4treated) were studied. The experiments were characterized by contact angle measurement,potentiodynamic polarization curve, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results showed that the adsorption behavior of MBTA on different treated surfaces was different and MBTA was preferentiallyadsorbed on the surface of citric acid treated copper. Based on the density functional theory, quantum chemicaldescriptors such as the frontier molecular orbital energies EHOMO,ELUMOand the energy gap between them, molecularelectrostatic potential, and Fukui function had been calculated and discussed. The adsorption mechanism of MBTA andcopper surface was further revealed, which had positive significance for the corrosion inhibition of copper surface in copperinterconnection CMP.

CRISPR/Cas9-mediated knockout of the Vanin-1 gene in the Leghorn Male Hepatoma cell line and its effects on lipid metabolism

Xu Lu,Wang Zhongliang,Liu Shihao,Wei Zhiheng,Yu Jianfeng,Li Jun,Li Jie,Yao Wen,Gu Zhiliang 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.3

Objective: Vanin-1 (VNN1) is a pantetheinase that catalyses the hydrolysis of pantetheine to produce pantothenic acid and cysteamine. Our previous studies have shown that the VNN1 is specifically expressed in chicken liver which negatively regulated by microRNA-122. However, the functions of the VNN1 in lipid metabolism in chicken liver haven’t been elucidated. Methods: First, we detected the VNN1 mRNA expression in 4-week chickens which were fasted 24 hours. Next, knocked out VNN1 via CRISPR/Cas9 system in the chicken Leghorn Male Hepatoma cell line. Detected the lipid deposition via oil red staining and analysis the content of triglycerides (TG), low-density lipoprotein-C (LDL-C), and highdensity lipoprotein-C (HDL-C) after VNN1 knockout in Leghorn Male Hepatoma cell line. Then we captured various differentially expressed genes (DEGs) between VNN1- modified LMH cells and original LMH cells by RNA-seq. Results: Firstly, fasting-induced expression of VNN1. Meanwhile, we successfully used the CRISPR/Cas9 system to achieve targeted mutations of the VNN1 in the chicken LMH cell line. Moreover, the expression level of VNN1 mRNA in LMH-KO-VNN1 cells decreased compared with that in the wild-type LMH cells (p<0.0001). Compared with control, lipid deposition was decreased after knockout VNN1 via oil red staining, meanwhile, the contents of TG and LDL-C were significantly reduced, and the content of HDL-C was increased in LMH-KO-VNN1 cells. Transcriptome sequencing showed that there were 1,335 DEGs between LMH-KO-VNN1 cells and original LMH cells. Of these DEGs, 431 were upregulated, and 904 were downregulated. Gene ontology analyses of all DEGs showed that the lipid metabolism-related pathways, such as fatty acid biosynthesis and long-chain fatty acid biosynthesis, were enriched. KEGG pathway analyses showed that “lipid metabolism pathway”, “energy metabolism”, and “carbohydrate metabolism” were enriched. A total of 76 DEGs were involved in these pathways, of which 29 genes were upregulated (such as cytochrome P450 family 7 subfamily A member 1, ELOVL fatty acid elongase 2, and apolipoprotein A4) and 47 genes were downregulated (such as phosphoenolpyruvate carboxykinase 1) by VNN1 knockout in the LMH cells. Conclusion: These results suggest that VNN1 plays an important role in coordinating lipid metabolism in the chicken liver.

A review on the risk, prevention and control of cooling water intake blockage in coastal nuclear power plants

Heshan Lin,Shuyi Zhang,Ranran Cao,Shihao Yu,Wei Bai,Rongyong Zhang,Jia Yang,Li Dai,Jianxin Chen,Yu Zhang,Hongni Xu,Kun Liu,Xinke Zhang Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.2

In recent decades, numerous instances of blockages have been reported in coastal nuclear power plants globally, leading to serious safety accidents such as power reduction, manual or automatic power loss, or shutdown of nuclear power units. Loss or shortage of cooling water may compromise the reliability of the cooling water system, thus threatening the operational safety of power plants and resulting in revenue reduction. This study provides a comprehensive review of the current state of cooling water system safety in coastal nuclear power plants worldwide and the common challenges they face, as well as the relevant research on cooling water system safety issues. The research overview and progress in investigation methods, outbreak mechanisms, prevention and control measures, and practical cases of blockages were summarized. Despite existing research, there are still many shortcomings regarding the pertinence, comprehensiveness and prospects of related research, and many problems urgently need to be solved. The most fundamental concern involves understanding the list of potential risks of blockages and their spatially distributed effects in surrounding waters. Furthermore, knowledge of the biological cycles and ecological habits of key organisms is essential for implementing risk prevention and control and for building a scientific and effective monitoring system.

Underwater superoleophobic copper mesh coated with block nano protrusion hierarchical structure for efficient oil/water separation

Xinyu Qi,Zhuwei Gao,Chengxin Li,Shihao Wang,Xin Zou,Lan He,Zhongxin Liu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-

Compared with monolayer nanosheet membranes, multilayer nanosheet membranes have low energyconsumption and can be mass-produced for industrial applications. Herein, a multi-layer nanostructuredmembrane, nickel-doped brochantite/Cu(OH)2 nano protrusion structure coated copper meshes(NBCPCMs), were successfully prepared. Firstly, the surface of the copper mesh was etched by chemicaloxidation to form a disordered copper hydroxide nanosheet layer. Secondly, the etched copper mesh surfacewas coated with nickel-controlled brochantite block-like protrusions by hydrothermal synthesismethod, and nickel-doped brochantite/Cu(OH)2 nanosheets were generated by high pressure. The resultsshowed that NBCPCM-4 had excellent hydrophilic/underwater superoleophobicity, the oil–water separationefficiency of immiscible cyclohexane/water mixture was the highest, about 98.54%, and still had avery high flux (>60 (kL/(hm2))) after multiple cycles of separation. In addition to ultra-high separationefficiency, NBCPCM-4 also had super durability. The copper mesh maintained good underwater superoleophobicityin different aqueous solutions. Therefore, NBCPCM-4 is a potential high-efficiency and sustainableoil–water separation membrane material. It is expected that the developed technology is usefulfor sea transportation and marine environment management, along with other industries.

Reliability Allocation Method for Remanufactured Machine Tools Based on Fuzzy Evaluation Importance and Failure Influence

Yan-bin Du,Guoao Wu,Ying Tang,Huajun Cao,Shihao Liu 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.6

Reliability is the key performance indicator for remanufactured machine tools to be approved by customers. Reliability allocation is an important task that needs to be done in the design phase of remanufactured machine tools to ensure that remanufactured products meet the reliability target requirements. A reliability allocation method for remanufactured machine tools is proposed based on fuzzy evaluation importance and failure influence of each component. The importance of each component is evaluated by five indicators such as complexity of structure, maturity of technology, criticality of fault, difficulty of maintenance, and severity of service condition, in which their weights are determined by the method of analytic hierarchy process (AHP). Failure influence is determined by the proportion of downtime caused by each component in total downtime of machine tools. Finally, the proposed method is illustrated in a numerical case study of NC lathe remanufacturing.