Springback analysis of the stiffened panel milling from the bent plate

Chun-Guo Liu,Tao Yue,Xiao-Tong Yu 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.2

An analytical method considering the redistribution of residual stress in the bent plate is proposed to predict the springback of the stiffened panel when milling the panel layer by layer. Two types of stiffened panel, namely, a panel with crosswise stiffeners and a panel with lengthwise stiffeners, were selected as examples and were analyzed during the removal of each layer. Moreover, a finite-element simulation of the milling process was conducted to make comparisons with the analytical results, which demonstrates similar stress distribution and springback values. The maximum stress variation and springback value appeared when the milling depth reached the initial neutral surface. When the plate thickness decreased, the errors between analytical results and FEM results increased, and the lengthwise-stiffened panel was less affected by errors than the crosswise-stiffened panel because of a larger moment of inertia. The effects of different milling thicknesses per layer, initial plate thickness, and bending radius were also analyzed. Moreover, the milling experiment was performed to make verification. The results suggest that the analytical method can predict the springback of the stiffened panel effectively. The proposed method can also be applied to other similar forming conditions.

Springback prediction method for double-curved workpiece considering plate anisotropy in multi-point forming

Chun-Guo Liu,Ming Li,Tao Yue 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

Springback is adversely affected by mechanical anisotropy in the process of sheet metal forming. In this work, an analytical method was proposed to predict the springback of the double-curved workpiece in multi-point forming process. To characterize the anisotropy of the AA7B04 aluminum plate, the plate was divided into several layers along thickness direction. And in each layer, the calculation of bending moment was done respectively based on von Mises, Hill’s 48 and Yld2004-18p yield criterion. After springback, the neutral surface curvature was calculated and the profile of the neutral surface was constructed by the Bezier surface blending method. To verify the prediction method, finite element simulation and bending experiment were performed. The results show that the predictive accuracy of the method was more accurate than that with the isotropy model. Additionally, the most accurate constitutive model to describe the in-plane anisotropy of AA7B04 aluminum was the Yld2004-18p yield criterion.

Key Application Technologies of High Efficiency Power Quality Control Systems

Liu, Ding-Guo,Shuai, Zhi-Kang,Tu, Chun-Ming,Cheng, Ying,Luo, An The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3

Large capacity reactive power compensation and harmonic control in the low-voltage grid of an enterprise, are important technical means to improve power quality and reduce power loss. In this paper, the principle of an efficient power quality controller is analyzed. Then, key application technologies of the HPQC which would influence the performances of the HPQC are studied. Based on an analysis of the harmonic shunt problem, a frequency dividing control strategy of the HPQC continuous subsystem is proposed. A parameter design method of the HPQC discrete subsystem and its installation method are also proposed to ensure the system compensation effect. HPQC systems have been designed for a copper foil plant. The effectiveness of this paper has been verified by the simulation and application results.

Case-control study on the fibroblast growth factor receptor 2 gene Polymorphisms associated with breast cancer in in Chinese Han women

Chun-Lian Liu,Xiao-Ping Hu,Wei-Dong Guo,Li Yang,Jie Dang,Hai-Yan Jiao 한국유방암학회 2013 Journal of breast cancer Vol.16 No.4

Purpose: Genetic variation in fibroblast growth factor receptor 2(FGFR2) is a newly described risk factor for breast cancer. Thisstudy aimed to evaluate the association of four single nucleotidepolymorphisms (SNPs) in FGFR2 with breast cancer in Han Chinesewomen. Methods: Two hundred three women with breastcancer and 200 breast cancer-free age-matched controls wereselected. Four SNPs (rs2981579, rs1219648, rs2420946, andrs2981582) and their haplotypes were analyzed to test for theirassociation with breast cancer susceptibility. The presence ofthe four FGFR2 SNPs was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Results:A statistically significant difference was observed in thefrequency of rs2981582 in the FGFR2 gene (p<0.05) betweencase and control groups. In subjects stratified by menopausalstatus, rs2981582 TT, rs2420946 AA, and rs1219648 CC weresignificantly associated with the risk of breast cancer in postmenopausalsubjects, but no significant associations betweenthese four SNPs and the risk of breast cancer were identified inpremenopausal subjects. Further, there was no significant associationbetween hormone receptor status (estrogen receptor andprogesterone receptor) and breast cancer risk. Six common (>3%) haplotypes were identified. Three of these haplotypes,CGTC (odds ratio [OR], 0.613; 95% confidence interval [CI],0.457-0.82; p=0.001), TGTC (OR, 6.561; 95% CI, 2.064-20.854;p<0.001), and CATC (OR, 12.645; 95% CI, 1.742-91.799; p=0.001) were significantly associated with breast cancer risk. Conclusion:Our findings indicated that the SNP rs2981582 and haplotypesCGTC, TGTC, and CATC in FGFR2 may be associatedwith an increased risk of breast cancer in Han Chinese women.

Lentivirus-mediated Silencing of Rhomboid Domain Containing 1 Suppresses Tumor Growth and Induces Apoptosis in Hepatoma HepG2 Cells

Liu, Xue-Ni,Tang, Zheng-Hao,Zhang, Yi,Pan, Qing-Chun,Chen, Xiao-Hua,Yu, Yong-Sheng,Zang, Guo-Qing Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

Rhomboids were identified as the first intramembrane serine proteases about 10 years ago. Since then, the study of the rhomboid protease family has blossomed. Rhomboid domain containing 1 (RHBDD1), highly-expressed in human testis, contains a rhomboid domain with unknown function. In the present study, we tested the hypothesis that RHBDD1 was associated with proliferation and apoptosis in hepatocellular carcinoma using recombinant lentivirus-mediated silencing of RHBDD1 in HepG2 cells. Our results showed that down-regulation of RHBDD1 mRNA levels markedly suppressed proliferation and colony formation capacity of HepG2 human hepatoma cancer cells in vitro, and induced cell cycle arrest. We also found that RHBDD1 silencing could obviously trigger HepG2 cell apoptosis. In summary, it was demonstrated that RHBDD1 might be a positive regulator for proliferative and apoptotic characteristics of hepatocellular carcinoma.

Impact of Allogenic and Autologous Transfusion on Immune Function in Patients with Tumors

Guo, Jian-Rong,Xu, Feng,Jin, Xiao-Ju,Shen, Hua-Chun,Liu, Yang,Zhang, Yi-Wei,Shao, Yi Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1

Objective: To observe the effects of allogeneic and autologous transfusion on cellular immunity, humoral immunity and secretion of serum inflammatory factors and perforin during the perioperative period in patients with malignant tumors. Methods: A total of 80 patients (age: 38-69 years; body weight: 40-78 kg; ASA I - II) receiving radical operation for gastro-intestinal cancer under general anesthesia were selected. All the patients were divided into four groups based on the methods of infusion and blood transfusion: blank control group (Group C), allogeneic transfusion group (group A), hemodiluted autotransfusion Group (Group H) and hemodiluted autotransfusion + allogenic transfusion Group (A+H group). Venous blood was collected when entering into the surgery room ($T_0$), immediately after surgery ($T_1$) and 24h ($T_2$), 3d ($T_3$) and 7d ($T_4$) after surgery, respectively. Moreover, flow cytometry was applied to assess changes of peripheral blood T cell subpopulations and NK cells. Enzyme linked immunosorbent assays were performed to determine levels of IL-2, IL-10, TNF-${\alpha}$ and perforin. Immune turbidimetry was employed to determine the changes in serum immunoglobulin. Results: Both CD3+ and NK cells showed a decrease at $T_1$ and $T_2$ in each group, among which, in group A, CD3+ decreased significantly at $T_2$ (P<0.05) compared with other groups, and CD3+ and NK cell reduced obviously only in group A at $T_3$ and $T_4$ (P<0.05). CD4+ cells and the ratio of D4+/CD8+ were decreased in groups A, C and A+H at $T_1$ and $T_2$ (P<0.05). No significant intra- and inter-group differences were observed in CD8+ of the four groups (P<0.05). IL-2 declined in group C at $T_1$ and $T_2$ (P<0.05) and showed a decrease in group A at each time point (P<0.05). Moreover, IL-2 decreased in group A + H only at $T_1$. No significant difference was found in each group at $T_1$ (P<0.05). More significant decrease in group ?? at $T_2$, $T_3$ and $T_4$ compared with group A (P<0.05), and there were no significant differences among other groups (P>0.05). IL-10 increased at $T_1$ and $T_2$ in each group (P<0.05), in which it had an obvious increase in group A, and increase of IL-10 occurred only in group A at $T_3$ and $T_4$ (P<0.05). TNF-${\alpha}$ level rose at $T_1$ (P<0.05), no inter- and intra-group difference was found in perforin in all groups (P<0.05). Compared with the preoperation, both IgG and IgA level decreased at $T_1$ in each group (P<0.05), and they declined only in Group A at $T_2$ and $T_3$ (P<0.05), and these parameters were back to the preoperative levels in other groups. No significant differences were observed between preoperative and postoperative IgG and IgA levels in each group at $T_4$ (P>0.05). No obvious inter- and intra-group changes were found in IgM in the four groups (P>0.05). Conclusions: Allogeneic transfusion during the perioperative period could obviously decrease the number of T cell subpopulations and NK cells and the secretion of stimulating cytokines and increase the secretion of inhibiting cytokines in patients with malignant tumors, thus causing a Th1/Th2 imbalance and transient decreasing in the content of plasma immune globulin. Autologous transfusion has little impact and may even bring about some improvement oo postoperative immune function in patients with tumors. Therefore, cancer patients should receive active autologous transfusion during the perioperative period in place of allogeneic transfusion.

Dynamics of Endogenous Phytohormones during Phase Change in Peach

Chun Min Li,Xin Zhong Zhang,Ya Qin Wu,Guo Jian Liu,Guang Peng Wang,Rui Feng Chang,Huai Rui Shu 한국원예학회 2008 한국원예학회 기타간행물 Vol.- No.-

Theoretical research on the identification method of bridge dynamic parameters using free decay response

Guo-jin Tan,Yong-chun Cheng,Han-bing Liu,Long-lin Wang 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.3

Input excitation and output response of structure are needed in conventional modal analysis methods. However, input excitation is often difficult to be obtained in the dynamic load test of bridge structures. Therefore, what attracts engineers’ attention is how to get dynamic parameters from the output response. In this paper, a structural experimental modal analysis method is introduced, which can be used to conveniently obtain dynamic parameters of the structure from the free decay response. With known damping coefficients, this analysis method can be used to identify the natural frequencies and the mode shapes of MDOF structures. Based on the modal analysis theory, the mathematical relationship of damping ratio and frequency is obtained. By using this mathematical relationship to improve the previous method, an improved experimental modal analysis method is proposed in this paper. This improved method can overcome the deficiencies of the previous method, which can not identify damping ratios and requires damping coefficients in advance. Additionally, this improved method can also identify the natural frequencies, mode shapes and damping ratios of the bridge only from the free decay response, and ensure the stability of identification process by using modern mathematical means. Finally, the feasibility and effectiveness of this method are demonstrated by a numerical example of a simply supported reinforced concrete beam.

Optical Properties of K9 Glass Waveguides Fabricated by Using Carbon-Ion Implantation

Chun-Xiao Liu,Wei Wei,Li-Li Fu,Xu-Feng Zhu,Hai-Tao Guo,Wei-Nan Li,She-Bao Lin 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.2

K9 glass is a material with promising properties that make it attractive for optical devices. Ion implantation is a powerful technique to form waveguides with controllable depth and refractive index profile. In this work, optical planar waveguide structures were fabricated in K9 glasses by using 6.0-MeV C3+-ion implantation with a fluence of 1.0 × 1015 ions/cm2. The effective refractive indices of the guided modes were measured by using a prism-coupling system. The refractive index change in the ion-irradiated region was simulated by using the intensity calculation method. The modal intensity profile of the waveguide was calculated and measured by using the finite difference beam propagation method and the end-face coupling technique, respectively. The transmission spectra before and after the implantation showed that the main absorption band was not influenced by the low fluence dopants. The optical properties of the carbon-implanted K9 glass waveguides show promise for use as integrated photonic devices.

Boundary Layer and Cooling Rate and Microstructure Formation on the Cooling Sloping Plate

Ren Guo Guan,Zhan Yong Zhao,Run Ze Chao,Lei Dong,이종수,Chun Ming Liu 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.5

During melt treatment by cooling sloping plate, laminar flow and turbulent flow exist on sloping plate surface commonly. The thickness of velocity boundary layer and the critical transfer distance from laminar flow to turbulent flow increase with the decrease of initial flow velocity. The thickness of temperature boundary layer increases with the increment of flow distance and the decrease of initial flow velocity. The melt cooling rate and melt thickness have an inverse proportion relationship. The melt cooling rate of cooling sloping plate process can reach 102-103 K/s and belongs to meta-rapid solidification scope. Uniform solute field and high cooling rate can lead to eruptive nucleation. In addition, a large quantity of heterogonous nuclei appears on the sloping plate surface, and vibrating flow can enable heterogonous nucleus to escape off the plate, which leads to nucleus multiplication. Under relative uniform solute field and high cooling rate, some grains can keep stable growth surface, go on growing with the round surface and finally maintain their globular structure. However, there are always some grains that grow along a certain preferred direction, but under vibrating flow their dendritic arms break and transform into near spherical structure.