Simulation and Experimental Investigation of Impact Damage in Composite Shell

Zhao, Gui Ping,Cho, Chong Du,Kwon, Oh Yang Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.297 No.-

<P>In this paper, the energy absorption characteristics on extruded aluminum box-section strengthened with carbon-fiber-reinforced plastics (CFRP) laminates and/or foam material were investigated under impact loading. Impact tests using a pneumatic impact tester were conducted with the specimens in three-point bending flexure with consideration given to the side-door impact beams in vehicles. The absorbed energy to the specimen during the impact was determined from the loaddisplacement curve, which was obtained from the strain gauge attached to the impactor and the laser displacement transducer. From the results, it was found that the strengthening by externally bonding with CFRP laminates improved the impact-induced energy absorption. Also, the effect of the improvement was clearly seen in the case of the use of filling form material in the aluminum extrusion together with attaching CFRP laminates.</P>

High-Velocity Impact of Carbon/Epoxy Composite Laminates

Zhao, Gui Ping,Wang, Zheng Hao,Zhang, Jian Xin,Cho, Chong Du Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.334-335 No.1

<P>The response of Carbon/epoxy composites under high velocity impact was investigated experimentally. The strain rate dependent behavior of T300 Carbon/epoxy matrix composite in tension is studied experimentally by split Hopkinson bar technique. Dynamic stress-strain plot was obtained and compared with the quasi-static tensile test results. The results of the study indicate that Carbon/epoxy composites are strain rate dependent materials. Stacking sequence has a significant effect on the material response. Tensile strength of the composites all increased with increasing strain rate. And failure strain decreased when strain rate increased.</P>

Large eddy simulation of flow around a stay cable with an artificial upper rivulet

Zhao, Yan,Du, Xiaoqing,Gu, Ming,Yang, Xiao,Li, Junjun,He, Ping Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.26 No.4

The appearance of a rivulet at the upper surface of a stay cable is responsible for rain-wind-induced vibration (RWIV) of cables of cable-stayed bridges. However, the formation mechanism of the upper rivulet and its aerodynamic effects on the stay cable has not been fully understood. Large eddy simulation (LES) method is used to investigate flow around and aerodynamics of a circular cylinder with an upper rivulet at a Reynolds number of 140,000. Results show that the mean lift coefficients of the circular cylinder experience three distinct stages, zero-lift stage, positive-lift stage and negative-lift stage as the rivulet located at various positions. Both pressure-induced and friction-induced aerodynamic forces on the upper rivulet are helpful for its appearance on the upside of the stay cable. The friction-induced aerodynamic forces, which have not been considered in the previous theoretical models, may not be neglected in modeling the RWIV. In positive-lift stage, the shear layer separated from the upper rivulet can reattach on the surface of the cylinder and form separation bubbles, which result in a high non-zero mean lift of the cylinder and potentially induces the occurrence of RWIV. The separation bubbles are intrinsically unsteady flow phenomena. A serial of small eddies first appears in the laminar shear layer separated from the upper rivulet, which then coalesces and reattaches on the side surface of the cylinder and eventually sheds into the wake.

Relative Risk of Metabolic Syndrome in Middle Aged Adults with Different Weight Living in Urban Beijing, China

Cui Zhao-Hui,Li Yan-Ping,Liu Ai-Ling,Zhang Qian,Du Wei-Jing,Ma Guan-Sheng The Korean Society of Community Nutrition 2004 Journal of community nutrition Vol.6 No.3

The purpose of this study is to compare the relative risk of metabolic syndrome (MS) in middle aged adults with different body weights. 155 subjects living in urban Beijing were recruited from 24 neighborhood committees of urban Beijing. They were divided into normal weight, overweight and obese groups according to their BMIs. The general information of the subjects was collected using an interview-administered questionnaire. Standard procedure was followed to measure subject's weight, height and waist. Biochemical parameters (total cholesterol (TC), low- and high­density lipoprotein cholesterol (LDL-C ; HDL-C), triglyceride (TG), and fasting glucose) and blood pressure were also determined. The results indicated that the systolic and diastolic blood pressure, HDL-C of obese group was lower than that of the normal weight group. Fasting glucose of obese males was significantly higher than that of normal weight males. No significant difference of fasting glucose was found among female groups. No significant difference of TG was found among male groups, while TG of overweight and obese females was both significantly higher than normal weight females. There was no significant difference of TC and LDL-C among normal weight, overweight and obese groups in both males and females. The MS rate of obese males was significantly higher than the normal weight and overweight males, as was the female. The relative risk of MS in obese group was about 11 times higher (OR=11.249, $95\%CI$ = 3.812 - 33.191) than the normal weight group after adjusting for age, gender, smoking, drinking, family economic level and education status. It is concluded that obesity contributed to lower HDL-C, hypertriglyceride, hypertension and MS after controlling the effects of age, gender, socioeconomic status, alcohol drinking and smoking. Obese individuals have a higher risk of having MS than their normal weight counterparts.

MiR-214 Regulates the Human Hair Follicle Stem Cell Proliferation and Differentiation by Targeting EZH2 and Wnt/b- Catenin Signaling Way In Vitro

Ke-Tao Du,Jia-Qin Deng,Xu-Guang He,Zhao-ping Liu,Cheng Peng,Mingsheng Zhang 한국조직공학과 재생의학회 2018 조직공학과 재생의학 Vol.15 No.3

miR-214 plays a major role in the self-renewal of skin tissue. However, whether miR-214 regulates the proliferation and differentiation of human hair follicle stem cells (HFSCs) is unknown. Primary HFSCs were isolated from human scalp skin tissue, cultured, and identified using flow cytometry. An miR-214 mimic and inhibitor were constructed for transfection into HFSCs. The MTS and colony formation assays examined cell proliferation. Immunofluorescence detected the localization and expression levels of TCF4, b-catenin, and differentiation markers. Luciferase reporter and TOP/FOP Flash assays investigated whether miR-214 targeted EZH2 and regulated the Wnt/b-catenin signaling pathway. Western blot determined the expression levels of enhancer of zeste homolog 2 (EZH2), Wnt/b-catenin signaling-related proteins, and HFSC differentiation markers in cells subjected to miR-214 transfection. miR-214 expression was remarkably decreased during the proliferation and differentiation of HFSCs into transit-amplifying (TA) cells. Downregulation of miR- 214 promotes the proliferation and differentiation of HFSCs. Overexpression of miR-214 led to decreased expression of EZH2, b-catenin, and TCF-4, whereas downregulation of miR-214 resulted in increased expression of EZH2, b-catenin, and TCF-4 as well as TA differentiation markers. Immunofluorescence assay revealed that inhibiting miR-214 triggered the entry of b-catenin and TCF-4 into the nucleus. The luciferase reporter and TOP/FOP Flash assays demonstrated that miR- 214 directly targets EZH2 and affects Wnt/b-catenin signaling. The miR-214/EZH2/b-catenin axis could be considered a candidate target in tissue engineering and regenerative medicine for HFSCs.

Nonlinear Finite Element Analysis of Composite Shell Under Impact

Cho, Chong-Du,Zhao, Gui-Ping,Kim, Chang-Boo The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.6

Large deflection dynamic responses of laminated composite cylindrical shells under impact are analyzed by the geometrically nonlinear finite element method based on a generalized Sander's shell theory with the first order transverse shear deformation and the von-Karman large deflection assumption. A modified indentation law with inelastic indentation is employed for the contact force. The nonlinear finite element equations of motion of shell and an impactor along with the contact laws are solved numerically using Newmark's time marching integration scheme in conjunction with Akay type successive iteration in each step. The ply failure region of the laminated shell is estimated using the Tsai- Wu quadratic interaction criteria. Numerical results, including the contact force histories, deflections and strains are presented and compared with the ones by linear analysis. The effect of the radius of curvature on the composite shell behaviors is investigated and discussed.

Influence of Heat Treatment on Microstructure and Mechanical Properties of TC4 Fabricated by Laser Melting Deposition

Qi Chaoqi,Du Yang,Yang Ping,Liu Zhengwu,Lyu Hongya,Zhao Kai,Guo Lijie 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

The phase composition, microstructure, tensile properties of TC4 samples produced by laser melting deposition (LMD)and LMD followed by solution-aging treatment were investigated to explore a simpler approach to improve the mechanicalperformances and eliminate negative influences by post treatment. The as-deposited TC4 microstructure showed a combinationof α΄martensite and α-colony with various shapes, such as acicular, rod-like and lamellar. As a synergistic result ofsolution and aging treatment, the dispersion strengthening of secondary-α as well as optimization on length-width ratio ofprimary-α and volume fraction of β-phase cause an increase in the ductility and strength. Meanwhile, there is a differencebetween microstructure of water-quenched specimens and air-cooled specimens, subsequently playing a key role in properties. The solution with air-cooling and aging is comparatively found to significantly reduce the anisotropy and improvecomprehensive performance.

Tug of War-Who is the Winner? Canker Disease Restructures the Endophytic Bacterial Community of Citrus

Jian-Yu Zhou,Yi Zhang,Wen-Ping Xu,Misbah Naz,Xiao-Meng Li,Xu Li,Bi-Ying Zhao,Shan-Shan Qi,Zhi-Cong Dai,Dao-Lin Du 한국원예학회 2023 원예과학기술지 Vol.41 No.5

High-throughput sequencing and a 16S rRNA gene clone library amplicon analysis were used to study the endophytic microbial diversity in citrus leaves in response to a Xanthomonas citri pv. Citri (Xcc) infection in an effort to develop a biocontrol scheme for citrus canker disease. There are more species of moderate citrus canker disease (MCD) than severe citrus canker disease (SCD) in terms of both Shannon and Simpson index measurements. Taxonomy has shown that the MCD Firmicutes group (25.2%) outnumber the SCD group (0.55%). Some Firmicutes can suppress Xcc, but in SCD leaves, they are in a competitive position and do not have a dominating niche; therefore, their population is greatly decreased. Sphingomonas and Methylobacterium, two genera of the phylum Proteobacteria, are growth-promoting and stress-resistant in most plants and comprise approximately 60% of the SCD group, whereas the MCD group was less abundant. In conclusion, citrus canker disease restructures bacterial communities in infected leaves, causing the endophytic community to evolve toward “weakening its spear and strengthening its shield.” This research provides support for the idea that introducing helpful bacterial strains in advance may alter the relative abundance of bacteria in a given area and hence decrease the likelihood of infection by harmful bacteria. The future of sequencing technology lies in research on microbial community functions, the elucidation of plant processes and pathogen occurrence, and support for the development of plant biological control technologies.

β-elemene Induces Caspase-dependent Apoptosis in Human Glioma Cells in vitro through the Upregulation of Bax and Fas/FasL and Downregulation of Bcl-2

Li, Chen-Long,Chang, Liang,Guo, Lin,Zhao, Dan,Liu, Hui-Bin,Wang, Qiu-Shi,Zhang, Ping,Du, Wen-Zhong,Liu, Xing,Zhang, Hai-Tao,Liu, Yang,Zhang, Yao,Xie, Jing-Hong,Ming, Jian-Guang,Cui, Yu-Qiong,Sun, Ying Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.23

Background: ${\beta}$-elemene, extracted from herb medicine Curcuma wenyujin has potent anti-tumor effects in various cancer cell lines. However, the activity of ${\beta}$-elemene against glioma cells remains unclear. In the present study, we assessed effects of ${\beta}$-elemene on human glioma cells and explored the underlying mechanism. Materials and Methods: Human glioma U87 cells were used. Cell proliferation was determined with MTT assay and colony formation assay to detect the effect of ${\beta}$-elemene at different doses and times. Fluorescence microscopy was used to observe cell apoptosis with Hoechst 33258 staining and change of glioma apoptosis and cell cycling were analyzed by flow cytometry. Real-time quantitative PCR and Western-blotting assay were performed to investigated the influence of ${\beta}$-elemene on expression levels of Fas/FasL, caspase-3, Bcl-2 and Bax. The experiment was divided into two groups: the blank control group and ${\beta}$-elemne treatment group. Results: With increase in the concentration of ${\beta}$-elemene, cytotoxic effects were enhanced in the glioma cell line and the concentration of inhibited cell viability ($IC_{50}$) was $48.5{\mu}g/mL$ for 24h. ${\beta}$-elemene could induce cell cycle arrest in the G0/G1 phase. With Hoechst 33258 staining, apoptotic nuclear morphological changes were observed. Activation of caspase-3,-8 and -9 was increased and the pro-apoptotic factors Fas/FasL and Bax were upregulated, while the anti-apoptotic Bcl-2 was downregulated after treatment with ${\beta}$-elemene at both mRNA and protein levels. Furthermore, proliferation and colony formation by U87 cells were inhibited by ${\beta}$-elemene in a time and does-dependent manner. Conclusions: Our results indicate that ${\beta}$-elemene inhibits growth and induces apoptosis of human glioma cells in vitro. The induction of apoptosis appears to be related with the upregulation of Fas/FasL and Bax, activation of caspase-3,-8 and -9 and downregulation of Bcl-2, which then trigger major apoptotic cascades.

Stabilization of Discrete-Time Networked Control Systems with Partly Known Transmission Delay: A New Augmentation Approach

Song-Lin Hu,Jin-Liang Liu,Zhao-Ping Du 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.6

This paper is concerned with the stabilization problem of discrete-time networked control systems with partly known transmission delay. Considering the random property of the networked-induced delay, the original system is transformed into a new delay model with stochastic parameter matrices by introducing a novel state augmentation technique. Based on the new model, a new delay-distribution-dependent criterion for the mean square stability of the closed-loop system is derived by using the Lyapunov-Krasovskii functional approach and linear matrix inequality technique. The solvability of the derived criterion depends on not only the size of the delay, but also the probability distribution of the delay taking value in a finite set. Finally, two numerical examples are given to demonstrate the effectiveness of the proposed method.