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Search Results: 1 - 10 of 12290 matches for " Zhimin XIE "
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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.
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.
Dynamic Viscoelasticity of Polyester/Rubber Composites under Cyclic Loading
Yuyan LIU,Zhenhui TIAN,Zhimin XIE,Xingwen DU,
Yuyan LUY
,Zhenhui TIAN,Zhimin XIE and Xingwen DU Harbin Institute of Technology,Harbin,China

材料科学技术学报 , 2005,
Abstract: This paper focuses on the influence of dynamic viscoelasticity and surface temperature on the fatigue mechanism and fatigue lifetime of polyester/rubber composites. Rubber composites show significant viscoelasticity during fatigue process. The variations of dynamic elastic modulus, mechanical loss angle, loss energy per cycle exhibit different trend in fatigue initial stage and final stage. Due to high viscoelasticity high heat generation occurs under cyclic loading, which leads to a high surface temperature. It is found that the variation of specimen surface temperaturedepends strongly on cycling frequency and stress amplitude. SEM (scanning electron microscopy) observation and static residual stiffness studies reveal that the surface temperature affects fracture morphology and fatigue lifetime of rubber composites strongly because of heat aging.
Chronic Toxicity Study in Rats Orally Exposed to Mulberry Sea-Buckthorn Beverage Concentrate  [PDF]
Qingping Sun, Zhimin Xu
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.59102

Objective: This study is designed to observe the chronic toxicity after the administration of mulberry sea-buckthorn beverage concentrate for 3 months on rats and to predict the possible adverse effect and the potential toxicity target organs. Method: The rats (SPF level) were randomly divided into high-dose (20 mL/kg BW), middle-dose (10 mL/kg BW), low-dose (5 mL/kg BW) groups and negative control group (20 mL/kg BW of purified water) with 30 rats in each group. Each group was orally given mulberry sea-buckthorn beverage concentrate for 3 months and recovered by stop feeding samples for 2 weeks for a recovery observation. The rats’ general condition, the organ coefficient, the indexes of hematology and blood biochemistry and the histological changes of the main organs were determined. Result: The appearance and behavior of activity in rats showed no anomalies in all these groups and all the rats put on weight during this period. Comparing to the negative control group, no obvious differences were observed in the weekly weight and organ coefficient of each dose group. After 3 months of administration, HGB in both mulberry sea-buckthorn beverage concentrate low-dose group and high-dose group were increased. No significant differences were observed in the indexes of hematology after 2 weeks of recovery. CREA in low-dose, middle-dose and high-dose groups were significantly increased after 3 months of administration and it remained in the high level in middle-dose and high-dose group even after 2 weeks of recovery. No drug-related lesions were observed in the histological changes of major organs. Conclusion: The results show that long term use of mulberry concentrated sea-buckthorn beverage can lead to increased CREA, which suggested kidney toxicity. Although no obvious pathological change was found in kidney, we should pay attention to chronic kidney damage in the further research.

Some New Delay Integral Inequalities Based on Modified Riemann-Liouville Fractional Derivative and Their Applications  [PDF]
Zhimin Zhao, Run Xu
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.35059
Abstract: By using the properties of modified Riemann-Liouville fractional derivative, some new delay integral inequalities have been studied. First, we offered explicit bounds for the unknown functions, then we applied the results to the research concerning the boundness, uniqueness and continuous dependence on the initial for solutions to certain fractional differential equations.
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.
Review of the monographMathematical Treatment and Application of Uncertain Information
Zhimin Yang
Chinese Science Bulletin , 2001, DOI: 10.1007/BF02900424
Pipelined Global Data Communication on Hypertoruses
计算机科学技术学报 , 1992,
Abstract: is paper presents several effective global data communication algorithms on the hypertorus,or kary n-cube interconnection network,which is a generalization of the conventional hypercube structure,The timing analysis of these algorithms is also gven.
Practice and Reflection on Interactive Three-Dimensional Teaching System in Agricultural and Forestry Colleges
Zhimin Lei
International Education Studies , 2013, DOI: 10.5539/ies.v6n3p221
Abstract: Ever since the new curriculum was implemented, Sichuan Agricultural University that is characterized by agricultural science has conducted ideological and political teaching reform, explored a basic route to integrate scientific outlook on development into theoretical teaching and initially formed a human-oriented interactive three-dimensional teaching system. In the practice of teaching reform, this university has insisted on healthy growth orientation of students and the basic principle of respecting students’ subjective status, stuck to the basic principle of the guiding position of Marxism and the leading position of students, set up the board of studies mechanism to direct students to take an initiative in participating in reform on theoretical teaching, constructed the self-education module of interaction of “explaining the theory” by students, set up the subjective teaching module of teaching leading and interaction between teachers and students and gradually formed the “quaternity” interactive teaching mode in which the four aspects of teachers and students, students and students, intracurricular and extracurricular resources and practice of students inside and outside the school interact with each other in an organic way. The result of the teaching reform practice is of demonstrative significance and promotion value.
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