Novel Water-Air Circulation Quenching Process for AISI 4140 Steel

Liyun Zheng,Dawei Zheng1,Lixin Zhao,Lihui Wang,Kai Zhang 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6

AISI 4140 steel is usually used after quenching and tempering. During the heat treatment process in industry production, there are some problems, such as quenching cracks, related to water-cooling and low hardness due to oil quenching. A water-air circulation quenching process can solve the problems of quenching cracks with water and the high cost quenching with oil, which is flammable, unsafe and not enough to obtain the required hardness. The control of the water-cooling and air-cooling time is a key factor in the process. This paper focuses on the quenching temperature, water-air cycle time and cycle index to prevent cracking for AISI 4140 steel. The optimum heat treatment parameters to achieve a good match of the strength and toughness of AISI 4140 steel were obtained by repeated adjustment of the water-air circulation quenching process parameters. The tensile strength, Charpy impact energy at -10 °C and hardness of the heat treated AISI 4140 steel after quenching and tempering were approximately 1098 MPa, 67.5 J and 316 HB, respectively.

Metadynamic and Static Recrystallization Softening Behavior of a Bainite Steel

Lixin Li,Liangyu Zheng,Ben Ye,Zeqiong Tong 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.1

The metadynamic recrystallization (MDRX) and static recrystallization (SRX) softening behavior of a bainitesteel was investigated by two-pass isothermal compression experiments at temperatures of 1173, 1273, 1373, and1473 K and strain rates of 0.01, 0.1, 1, and 10 s-1with inter-pass times of 1, 5, 10, and 30 s on a Gleeble-1500thermo-mechanical simulator. Kinetic equations were developed to evaluate the softening fractions caused byMDRX and SRX. A comparison between the experimental and predicted softening fractions showed that the proposedkinetic equations can provide a precise estimation of the MDRX and SRX behavior of the studied steel. Theresults based on the kinetic equations indicated that the MDRX and SRX softening fraction increases with theincrease in strain rate, deformation temperature, inter-pass time, and pre-strain; the activation energy of MDRX ismuch smaller than that of SRX; and the no-recrystallization temperature of the investigated steel is 1179.4 K.

BRAF-Activated Long Noncoding RNA Modulates Papillary Thyroid Carcinoma Cell Proliferation through Regulating Thyroid Stimulating Hormone Receptor

Haitao Zheng,Meng Wang,Lixin Jiang,Haidi Chu,Jinchen Hu,Jinyao Ning,Baoyuan Li,Dong Wang,Jie Xu 대한암학회 2016 Cancer Research and Treatment Vol.48 No.2

Purpose The importance of long noncoding RNAs (lncRNAs) in tumorigenesis has recently been demonstrated. However, the role of lncRNAs in development of thyroid cancer remains largely unknown. Materials and Methods Using quantitative reverse transcription polymerase chain reaction, expression of three lncRNAs, including BRAF-activated long noncoding RNA (BANCR), papillary thyroid cancer susceptibility candidate 3 (PTCSC3), and noncoding RNA associated with mitogen-activated protein kinase pathway and growth arrest (NAMA), was investigated in the current study. Results Of the three lncRNAs (BANCR, PTCSC3, and NAMA), expression of BANCR was significantly up-regulated while PTCSC3 and NAMA were significantly down-regulated in papillary thyroid carcinoma (PTC) compared to that in normal tissue. BANCR-knockdown in a PTC-derived cell line (IHH-4) resulted in significant suppression of thyroid stimulating hormone receptor (TSHR). BANCR-knockdown also led to inhibition of cell growth and cell cycle arrest at G0/G1 phase through down-regulation of cyclin D1. In addition, BANCR was enriched by polycomb enhancer of zeste homolog 2 (EZH2), and silencing BANCR led to decreased chromatin recruitment of EZH2, which resulted significantly reduced expression of TSHR. Conclusion These findings indicate that BANCR may contribute to the tumorigenesis of PTC through regulation of cyclin D1 and TSHR.

Research on Fixture Hole Drilling Quality of Printed Circuit Board

Xiaohu Zheng,Dapeng Dong,Lixin Huang,Qinglong An,Xibin Wang,Ming Chen 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

Printed circuit board (PCB) fixture hole is used for installing PCB board or fixing PCB board during drilling process. The drilling quality parameters involve burr size, hole wall roughness et al. In order to improve drilling quality, proper drilling parameters and tool geometries are important especially the tool geometries. In this study, the drilling machinability of PCB fixture hole is studied,effects of drilling parameters on thrust force, drilling temperature and quality are discussed. The experimental results show that resin will be melted during the drilling process. The increase in spindle speed will lead to drilling temperature rise. The fuzzing and spalling of glass fibers result in the generation of hole wall roughness. The exit burrs and enter burrs are generated from drilling copper foils which located in the upper and lower surfaces. The heights of exit burrs are increased with the elevated feed. Drilling experiments are carried out with 9 drill bits which have different point angles, helix angles and length of chisel edges. Analysis of variance (ANOVA) is carried out for hole quality parameters. Desirability function method is used in multiple response optimization to obtain the optimal tool geometry parameters.

Thermodynamics stability, electronic structures and spectroscopic properties of defects and Ce3+ ions in Y2O3

Wang Yan,Wen Jun,Zheng Jiangyun,Deng Zhifeng,Zhou Yueyu,Jiang Guisheng,Xia Qiangsheng,He Enjie,Ning Lixin 한국물리학회 2021 Current Applied Physics Vol.26 No.-

Thermodynamic properties, electronic structures and spectroscopic properties of defects and Ce3+ in Y2O3 are studied by using the hybrid density functional theory associated with multi-reference configuration interaction ab-initio calculations. Thermodynamic transition energy levels of the easily generated oxygen vacancies in the host are analyzed according to HSE06-calculated formation energies, which may be conducive to interpretations of the persistent luminescence (PersL) of Y2O3-based phosphors. Besides, the locations of impurity states (caused by VO and Ce3+) in energy bands are obtained from derived density of states. Moreover, energies and oscillator strengths of 4f1 → 5d1 5 transitions of Ce3+ ions (at Y1 and Y2 sites) calculated from the CASSCF/CASPT2/ RASSI SO method agree reasonably well with experimental excitation spectra of Y2O3: Ce3+ phosphors, achieving the assignment of excitation spectra. The presented calculations can be applied to identify luminescent centers in Ce3+-doped phosphors and reveals possible native defects and their roles in the PersL of phosphors.

Distinct Transcriptional and Functional Differences of Lung Resident and Monocyte-Derived Alveolar Macrophages During the Recovery Period of Acute Lung Injury

Hou Fei,Wang Huan,Zheng Kun,Yang Wenting,Xiao Kun,Rong Zihan,Xiao Junjie,Li Jing,Cheng Baihe,Tang Li,Xie Lixin 대한면역학회 2023 Immune Network Vol.23 No.3

In acute lung injury, two subsets of lung macrophages exist in the alveoli: tissue-resident alveolar macrophages (AMs) and monocyte-derived alveolar macrophages (MDMs). However, it is unclear whether these 2 subsets of macrophages have different functions and characteristics during the recovery phase. RNA-sequencing of AMs and MDMs from the recovery period of LPS-induced lung injury mice revealed their differences in proliferation, cell death, phagocytosis, inflammation and tissue repair. Using flow cytometry, we found that AMs showed a higher ability to proliferate, whereas MDMs expressed a larger amount of cell death. We also compared the ability of phagocytosing apoptotic cells and activating adaptive immunity and found that AMs have a stronger ability to phagocytose, while MDMs are the cells that activate lymphocytes during the resolving phase. By testing surface markers, we found that MDMs were more prone to the M1 phenotype, but expressed a higher level of pro-repairing genes. Finally, analysis of a publicly available set of single-cell RNA-sequencing data on bronchoalveolar lavage cells from patients with SARS-CoV-2 infection validated the double-sided role of MDMs. Blockade of inflammatory MDM recruitment using CCR2−/− mice effectively attenuates lung injury. Therefore, AMs and MDMs exhibited large differences during recovery. AMs are long-lived M2-like tissue-resident macrophages that have a strong ability to proliferate and phagocytose. MDMs are a paradoxical group of macrophages that promote the repair of tissue damage despite being strongly pro-inflammatory early in infection, and they may undergo cell death as inflammation fades. Preventing the massive recruitment of inflammatory MDMs or promoting their transition to pro-repairing phenotype may be a new direction for the treatment of acute lung injury.

Robust video watermarking algorithm for H.264/AVC based on JND model

( Weiwei Zhang ),( Xin Li ),( Yuzhao Zhang ),( Ru Zhang ),( Lixin Zheng ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.5

With the purpose of copyright protection for digital video, a novel H.264/AVC watermarking algorithm based on JND model is proposed. Firstly, according to the characteristics of human visual system, a new and more accurate JND model is proposed to determine watermark embedding strength by considering the luminance masking, contrast masking and spatial frequency sensitivity function. Secondly, a new embedding strategy for H.264/AVC watermarking is proposed based on an analysis on the drift error of energy distribution. We argue that more robustness can be achieved if watermarks are embedded in middle and high components of 4×4 integer DCT since these components are more stable than dc and low components when drift error occurs. Finally, according to different characteristics of middle and high components, the watermarks are embedded using different algorithms, respectively. Experimental results demonstrate that the proposed watermarking algorithm not only meets the imperceptibility and robustness requirements, but also has a high embedding capacity.

Reformability evaluation of blasting-enhanced permeability in in situ leaching mining of low-permeability sandstone-type uranium deposits

Wang Wei,Liang Xuanyu,Niu Qinghe,Wang Qizhi,Zhuo Jinyi,Su Xuebin,Zhou Genmao,Zhao Lixin,Yuan Wei,Chang Jiangfang,Zheng Yongxiang,Pan Jienan,Wang Zhenzhi,Ji Zhongmin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

It is essential to evaluate the blasting-enhanced permeability (BEP) feasibility of a low-permeability sandstone-type uranium deposit. In this work, the mineral composition, reservoir physical properties and rock mechanical properties of samples from sandstone-type uranium deposits were first measured. Then, the reformability evaluation method was established by the analytic hierarchy process-entropy weight method (AHP-EWM) and the fuzzy mathematics method. Finally, evaluation results were verified by the split Hopkinson Pressure Bar (SHPB) experiment and permeability test. Results show that medium sandstone, argillaceous sandstone and siltstone exhibit excellent reformability, followed by coarse sandstone and fine sandstone, while the reformability of sandy mudstone is poor and is not able to accept BEP reservoir stimulation. The permeability improvement and the distribution of damage fractures before and after the SHPB experiment confirm the correctness of evaluation results. This research provides a reformability evaluation method for the BEP of the low-permeability sandstone-type uranium deposit, which contributes to the selection of the appropriate regional and stratigraphic horizon of the BEP and the enhanced ISL of the low-permeability sandstone-type uranium deposit.

Decentralized Multiple Control for DC Microgrid with Hybrid Energy Storage

Li Xin,Zheng Taoyin,Guo Panfeng,Huang Jianan,Li Xinyu,Xiong Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

For a microgrid with hybrid energy storage system , unreasonable power distribution, significant voltage deviation and state-of-charge (SOC) violation are major issues. Conventionally, they are achieved by introducing communication into centralized control or distributed control. This paper proposes a decentralized multiple control to enhance the performance of the system. A low-pass filter based on droop control is applied to battery energy storage system (BESS), and a low-pass difference filter based on proportional-integral (PI) voltage regulation is employed for supercapacitor (SC). The cooperation between them realizes power distribution, in which the average power is compensated by BESS and the high-frequency fluctuation is suppressed by SC. Meanwhile, the voltage deviation is diminished through mode re-division. Considering the SOC imbalance of BESSs and SOC violation of SC, current correction and voltage compensation methods based on local information are proposed to optimize the current sharing of BESSs and ensure the availability of SC, respectively. The advantage of voltage compensation is that, the SC is still available in process of SOC recovery. The simulation model is established on the MATLAB/Simulink environment and the feasibility of proposed strategy is verified by simulation analysis in different scenarios.