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Search Results: 1 - 10 of 129297 matches for " Youshan WANG Zhimin XIE "
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Experimental Investigation of Folding Damage for the Rigidizable Carbon-Epoxy Composites
Youshan WANG,Zhimin XIE,Zhimin WAN,Xingwen DU,
Youshan WANG Zhimin XIE
,Zhimin WAN and Xingwen DU Center for Composite Materials,Harbin Institute of Technology,Harbin,China Analysis and Measurement Center,Harbin Institute of Technology,Harbin,China

材料科学技术学报 , 2005,
Abstract: This paper focused on the folding damage behavior of the space rigidizable materials in terms of 3-layer composite membranes. An experimental scheme was presented. The composite membranes were folded between the two plates for a short time, and then the unfolded composite membranes were compressively cured in an oven. By adjusting the displacement of one plate, the folding radius was changed. As expected, the strength and effective modulus of the cured composite membranes drop with decreasing the folding radius. When the strain controlled failure rule is applied to the composite membranes, a minimal folding radius can be reached, beyond which the membranes will keep intact. Furthermore, folding damage due to folding and unfolding processes was evaluated by a simplified model. Compared with the measured residual strength and effective modulus, calculated results have the same trend. A discrepancy is attributed to neglecting the effects of the transverse fibers and the matrix.
Effects of Fertilization and Clipping on Carbon, Nitrogen Storage, and Soil Microbial Activity in a Natural Grassland in Southern China
Zhimin Du, Yan Xie, Liqun Hu, Longxing Hu, Shendong Xu, Daoxin Li, Gongfang Wang, Jinmin Fu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099385
Abstract: Grassland managements can affect carbon (C) and nitrogen (N) storage in grassland ecosystems with consequent feedbacks to climate change. We investigated the impacts of compound fertilization and clipping on grass biomass, plant and soil (0–20 cm depth) C, N storage, plant and soil C: N ratios, soil microbial activity and diversity, and C, N sequestration rates in grassland in situ in the National Dalaoling Forest Park of China beginning July, 2011. In July, 2012, the fertilization increased total biomass by 30.1%, plant C by 34.5%, plant N by 79.8%, soil C by 18.8% and soil N by 23.8% compared with the control, respectively. Whereas the clipping decreased total biomass, plant C and N, soil C and N by 24.9%, 30.3%, 39.3%, 18.5%, and 19.4%, respectively, when compared to the control. The plant C: N ratio was lower for the fertilization than for the control and the clipping treatments. The soil microbial activity and diversity indices were higher for the fertilization than for the control. The clipping generally exhibited a lower level of soil microbial activity and diversity compared to the control. The principal component analysis indicated that the soil microbial communities of the control, fertilization and clipping treatments formed three distinct groups. The plant C and N sequestration rates of the fertilization were significantly higher than the clipping treatment. Our results suggest that fertilization is an efficient management practice in improving the C and N storage of the grassland ecosystem via increasing the grass biomass and soil microbial activity and diversity.
A Multilevel Correction Scheme for Nonsymmetric Eigenvalue Problems by Finite Element Methods
Hehu Xie,Zhimin Zhang
Mathematics , 2015,
Abstract: A multilevel correction scheme is proposed to solve nonsymmetric eigenvalue problems by the finite element method. The method includes multi correction steps in a sequence of finite element spaces. In each correction step, we only need to solve two source problems on a finer finite element space and two eigenvalue problems on the coarsest finite element space. The accuracy of the eigenpair approximation is improved after each correction step. This correction scheme improves overall efficiency of the finite element method in solving nonsymmetric eigenvalue problems.
Sharp Error Bounds for Piecewise Polynomial Approximation: Revisit and Application to Elliptic PDE Eigenvalue Computation
Hehu Xie,Zhimin Zhang
Mathematics , 2015,
Abstract: In this paper, we revisit approximation properties of piecewise polynomial spaces, which contain more than ${\cal P}_{r-1}$ but not ${\cal P}_r$. We develop more accurate upper and lower error bounds that are sharper than those used in literature. These new error bounds, especially the lower bounds are particular useful to finite element methods. As an important application, we establish sharp lower bounds of the discretization error for Laplace and $2m$-th order elliptic eigenvalue problems in various finite element spaces under shape regular triangulations, and investigate the asymptotic convergence behavior for large numerical eigenvalue approximations.
A New Conjugate Gradient Projection Method for Solving Stochastic Generalized Linear Complementarity Problems  [PDF]
Zhimin Liu, Shouqiang Du, Ruiying Wang
Journal of Applied Mathematics and Physics (JAMP) , 2016, DOI: 10.4236/jamp.2016.46107
Abstract: In this paper, a class of the stochastic generalized linear complementarity problems with finitely many elements is proposed for the first time. Based on the Fischer-Burmeister function, a new conjugate gradient projection method is given for solving the stochastic generalized linear complementarity problems. The global convergence of the conjugate gradient projection method is proved and the related numerical results are also reported.
Towards the Availability of the Distributed Cluster Rendering System: Automatic Modeling and Verification
Kemin Wang,Zhengtao Jiang,Yongbin Wang,Youshan Yang
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: In this study, we proposed a Continuous Time Markov Chain Model towards the availability of n-node clusters of Distributed Rendering System. It’s an infinite one, we formalized it, based on the model, we implemented a software, which can automatically model with PRISM language. With the tool, whenever the number of node-n and related parameters vary, we can create the PRISM model file rapidly and then we can use PRISM model checker to verify ralated system properties. At the end of this study, we analyzed and verified the availability distributions of the Distributed Cluster Rendering System while the node number-n varying under different repair modes.
M3 Subtype of Muscarinic Acetylcholine Receptor Promotes Cardioprotection via the Suppression of miR-376b-5p
Zhenyu Pan,Yueping Guo,Hanping Qi,Kai Fan,Shu Wang,Hua Zhao,Yuhua Fan,Jing Xie,Feng Guo,Yunlong Hou,Ning Wang,Rong Huo,Yong Zhang,Yan Liu,Zhimin Du
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032571
Abstract: The M3 subtype of muscarinic acetylcholine receptors (M3-mAChR) plays a protective role in myocardial ischemia and microRNAs (miRNAs) participate in many cardiac pathophysiological processes, including ischemia-induced cardiac injury. However, the role of miRNAs in M3-mAChR mediated cardioprotection remains unexplored. The present study was designed to identify miRNAs that are involved in cardioprotective effects of M3-mAChR against myocardial ischemia and elucidate the underlying mechanisms. We established rat model of myocardial ischemia and performed miRNA microarray analysis to identify miRNAs involved in the cardioprotection of M3-mAChR. In H9c2 cells, the viability, intracellular free Ca2+ concentration ([Ca2+]i), intracellular reactive oxygen species (ROS), miR-376b-5p expression level, brain derived neurophic factor (BDNF) and nuclear factor kappa-B (NF-κB) levels were measured. Our results demonstrated that M3-mAChR protected myocardial ischemia injury. Microarray analysis and qRT-PCR revealed that miR-376b-5p was significantly up-regulated in ischemic heart tissue and the M3-mAChRs agonist choline reversed its up-regulation. In vitro, miR-376b-5p promoted H2O2-induced H9c2 cell injuries measured by cells viability, [Ca2+]i and ROS. Western blot and luciferase assay identified BDNF as a direct target of miR-376b-5p. M3-mAChR activated NF-κB and thereby inhibited miR-376b-5p expression. Our data show that a novel M3-mAChR/NF-κB/miR-376b-5p/BDNF axis plays an important role in modulating cardioprotection. MiR-376b-5p promotes myocardial ischemia injury possibly by inhibiting BDNF expression and M3-mAChR provides cardioprotection at least partially mediated by the downregulation of miR-376b-5p through NF-κB. These findings provide new insight into the potential mechanism by which M3-mAChR provides cardioprotection against myocardial ischemia injury.
Boundedness in a two-dimensional chemotaxis-haptotaxis system
Youshan Tao
Mathematics , 2014,
Abstract: This work studies the chemotaxis-haptotaxis system $$\left\{ \begin{array}{ll} u_t= \Delta u - \chi \nabla \cdot (u\nabla v) - \xi \nabla \cdot (u\nabla w) + \mu u(1-u-w), &\qquad x\in \Omega, \, t>0, \\[1mm] v_t=\Delta v-v+u, &\qquad x\in \Omega, \, t>0, \\[1mm] w_t=-vw, &\qquad x\in \Omega, \, t>0, \end{array} \right. $$ in a bounded smooth domain $\Omega\subset\mathbb{R}^2$ with zero-flux boundary conditions, where the parameters $\chi, \xi$ and $\mu$ are assumed to be positive. It is shown that under appropriate regularity assumption on the initial data $(u_0, v_0, w_0)$, the corresponding initial-boundary problem possesses a unique classical solution which is global in time and bounded. In addition to coupled estimate techniques, a novel ingredient in the proof is to establish a one-sided pointwise estimate, which connects $\Delta w$ to $v$ and thereby enables us to derive useful energy-type inequalities that bypass $w$. However, we note that the approach developed in this paper seems to be confined to the two-dimensional setting.
Genome-Wide Identification and Immune Response Analysis of Serine Protease Inhibitor Genes in the Silkworm, Bombyx mori
Ping Zhao, Zhaoming Dong, Jun Duan, Genhong Wang, Lingyan Wang, Youshan Li, Zhonghuai Xiang, Qingyou Xia
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031168
Abstract: In most insect species, a variety of serine protease inhibitors (SPIs) have been found in multiple tissues, including integument, gonad, salivary gland, and hemolymph, and are required for preventing unwanted proteolysis. These SPIs belong to different families and have distinct inhibitory mechanisms. Herein, we predicted and characterized potential SPI genes based on the genome sequences of silkworm, Bombyx mori. As a result, a total of eighty SPI genes were identified in B. mori. These SPI genes contain 10 kinds of SPI domains, including serpin, Kunitz_BPTI, Kazal, TIL, amfpi, Bowman-Birk, Antistasin, WAP, Pacifastin, and alpha-macroglobulin. Sixty-three SPIs contain single SPI domain while the others have at least two inhibitor units. Some SPIs also contain non-inhibitor domains for protein-protein interactions, including EGF, ADAM_spacer, spondin_N, reeler, TSP_1 and other modules. Microarray analysis showed that fourteen SPI genes from lineage-specific TIL family and Group F of serpin family had enriched expression in the silk gland. The roles of SPIs in resisting pathogens were investigated in silkworms when they were infected by four pathogens. Microarray and qRT-PCR experiments revealed obvious up-regulation of 8, 4, 3 and 3 SPI genes after infection with Escherichia coli, Bacillus bombysepticus, Beauveria bassiana or B. mori nuclear polyhedrosis virus (BmNPV), respectively. On the contrary, 4, 11, 7 and 9 SPI genes were down-regulated after infection with E. coli, B. bombysepticus, B. bassiana or BmNPV, respectively. These results suggested that these SPI genes may be involved in resistance to pathogenic microorganisms. These findings may provide valuable information for further clarifying the roles of SPIs in the development, immune defence, and efficient synthesis of silk gland protein.

Zhang Meiqing Wang Youshan Zhang Chi,

菌物学报 , 1994,
Abstract: The work was carried out in the area of 1,790,000 Sq. Km. of northern China. The results were as follows: The distribution of some genera and species of VAMF shows regional difference. Glomus is dominant genus in the area. The distribution of some genera and species of VAMF has relation to soil pH, the content of soil organic matter(OM), and elevation of collecting sites. Within pH 5-9.5 the greater of soil alkalinity the more Glomus were found, the greater of soil acidity the more Acaulospora were observed. There was no Scutellospora in soil whose pH was greater than 9. Less Glomus existed in soil whose content of OM was greater than 10 %, but Glomus sp.9 mainly occurred in soil which was rich in OM. Some Acaulospora species showed certain selectivity to the content of OM. Generally more Scutellospora could be isolated from soil with high content of OM. When elevation was over 3000M, Glomus and Acaulospora decreased rapidly, and Scutellospora was never found. Some species in Glomus were more sensitive to elevation. Six species were found in 21 soil samples which irrigated with sewage for more than 20 years in Beijing. G. mosseae was the most common species either in sewage irrigation soil or in investigated area. VAM fungi are divided into euryeco-logical type and stenoecological type according to different adaptability and selectivity to environment and reginity.
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