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Search Results: 1 - 10 of 51028 matches for " Demin Wei "
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Fracture and Damage Behaviors of Concrete in the Fractal Space  [PDF]
Heng Zhang, Demin Wei
Journal of Modern Physics (JMP) , 2010, DOI: 10.4236/jmp.2010.11006
Abstract: The fracture toughness, the driving force and the fracture energy for an infinite plate with a fractal crack are investigated in the fractal space in this work. The perimeter-area relation is adopted to derive the transforma-tion rule between damage variables in the fractal space and Euclidean space. A plasticity yield criterion is introduced and a damage variable tensor is decomposed into tensile and compressive components to describe the distinct behaviors in tension and compression. A plastic damage constitutive model for concrete in the Euclidean space is developed and generalized to fractal case according to the transformation rule of damage variables. Numerical calculations of the present model with and without fractal are conducted and compared with experimental data to verify the efficiency of this model and show the necessity of considering the fractal effect in the constitutive model of concrete. The structural response and mesh sensitivity of a notched unre-inforced concrete beam under 3-point bending test are theoretical studied and show good agreement with the experimental data.

WEI Demin,ZHANG Heng,

力学与实践 , 2008,
Abstract: In this paper, the effect of the section size on the strain energy of vaulting poles is investigated in the static equilibrium condition. The variation of the wall thickness of the vaulting pole along its length is obtained. The deformation curve of the vaulting pole under the ultimate state is computed by Finite Element Method, and the assumption that the ultimate deformation curve is in a form of arc is verified as well. The performance index is modified based on the energy conservation, taking into account the contribution of the vaulter's muscle work to the height of pole vaulting. The computational formula of the vaulting height is derived as a function of the weight, the height of athletes and the pole grasp height.


力学与实践 , 2007,
Abstract: The stability of thin-walled structures is an important problem in civil engineering.In this paper,the nonlinear elastic buckling of the open thin-walled curved-beam is analyzed by using the finite element method. Through the nonlinear regression computation for a great number of Finite-Element results,a practical and simple formula is obtained,which can be used to estimate the ultimate bearing capacity of the open thin-walled curved beams.
Fibroblast-Like Cells Differentiated from Adipose-Derived Mesenchymal Stem Cells for Vocal Fold Wound Healing
Rong Hu, Wei Ling, Wen Xu, Demin Han
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0092676
Abstract: Tissue engineering has revealed the potential to regenerate injured vocal folds, and identification of the most suitable seed cells has remained a hot topic of research. The aim of this study was to implant fibroblast-like cells differentiated from adipose-derived mesenchymal stem cells (ADSCs) in a canine acute vocal fold wound model. We then sought to characterize changes in the extracellular matrix (ECM) proteins of vocal fold lamina propria. For this purpose, ADSCs were induced to differentiate into fibroblasts under the regulation of connective tissue growth factor in vitro. Cell surface proteins were identified by immunofluorescence staining. Thirty vocal folds of 17 canines were injured by localized resection and injected with fibroblast-like cells (differentiated ADSCs, dADSCs), ADSCs or vocal fold fibroblasts (VFFs). The morphology of vocal folds was observed, and the characteristics of ECM protein components (collagen, elastin, hyaluronic acid, decorin and fibronectin) were evaluated by immunofluorescence staining from 15 days to 6 months following implantation. The results showed that in vitro, the dADSCs showed morphology and cell surface protein expression similar to those of VFFs. After implantation in vivo, the surfaces of the recipient vocal folds became almost smooth in the dADSCs and ADSCs groups at 6 months but remained slightly concave and stiff in the VFFs group. The elastin fluorescence intensity increased significantly and was maintained at a high level in the dADSCs group. The collagen fluorescence intensity increased slightly in the dADSCs and ADSCs groups, whereas it demonstrated a more irregular arrangement in the VFFs group. The fluorescence intensity of hyaluronic acid, decorin and fibronectin was similar between the three implanted groups. These results indicated that dADSCs may confer an advantage for vocal fold wound healing. Furthermore, dADSCs have the ability to secrete ECM components in vivo, particularly elastin, which may be beneficial for vocal fold vibration recovery.
Association Pattern of Interleukin-1 Receptor-Associated Kinase-4 Gene Polymorphisms with Allergic Rhinitis in a Han Chinese Population
Yuan Zhang,Xiaoping Lin,Martin Desrosiers,Wei Zhang,Na Meng,Liping Zhao,Demin Han,Luo Zhang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021769
Abstract: Interleukin-1 receptor-associated kinase-4 (IRAK-4) encodes a kinase that is essential for NF-kB activation in Toll-like receptor and T-cell receptor signaling pathways, indicating a possible crosstalk between innate and acquired immunities. We attempted to determine whether the polymorphisms in the Interleukin-1 receptor-associated kinase-4 (IRAK-4) gene are associated with allergic rhinitis (AR) in the Han Chinese population.
Relationship between the acidity of precipitation and the synoptic situation in Shanghai

Shao Demin,Zhang Wei,He Zhenzhen and,

大气科学 , 1987,
Abstract: 1981—1983年在上海地区11个观测站进行了雨水pH值观测,取到资料2448份.从资料分析得到:(1)雨水pH值与天气背景有关,静止锋天气影响时,酸雨出现几率达44.5%,雨水较酸;暖锋天气时,酸雨出现几率仅9%.(2)台风、高压边缘天气影响下,酸雨的形成主要是受局地污染源的影响;但静止锋、冷锋、低压系统天气时,酸雨的形成不仅受局地污染源的影响,而且还可能受随气流输送来的外来污染物的影响.
An Analysis of the Air Parcel Trajectories of Long-Range Transport at Shanghai

Shao Demin,Zhang Wei,Shen Aihu,Cheng Xueqing,Fu Zhemin,He Zhenzhen,

大气科学进展 , 1992,
Abstract: CONCLUSION The analysis of air parcel trajectories affecting Shanghai indicates that the coming-direction of air parcel is different in various months. The transport track of trajectory (backward and forward) is closely related to the synoptic system, and also related to acid rain occurring in Shanghai region. Air pollution and acid rain in Shanghai region have relationship with both the influence of local pollutants and the influence of external pollutants from southwest and northeast.

WEI Demin,CHEN Yuqing,

力学与实践 , 2006,
Abstract: The ultimate bearing capacity of curved beams is related with the bending-torsion strength and the stability. With elastic-plastic deformation, the bending stress and the torsion stress are not linear with respect to the strain, so the problem will be more complicated. In this paper, using different formulae of the ultimate capacity of curved beams, a regression model is obtained. Through the nonlinear regression Calculation for a lot of computational results obtained by using the finite element method, a simplified and useful calculation formula is proposed, which can be used in the practical design of the curved beams.

XIA Jianming,WEI Demin,

力学与实践 , 2008,
Abstract: The recent advances in continuum methods for carbon nanotubes are presented. The continuum methods for carbon nanotubes as beam/shell/membrane models, multi-scale methods, molecular structural mechanics methods, nonlocal continuum methods, and meshless methods are described. This paper presents the theorem and methodology of these methods and their recent advances, and predicts the future studies in carbon nanotubes with the continuum methods.
邵德民 Shao Demin,张维 Zhang Wei,沈爱华 He Zhenzhen,等 et al
大气科学 , 1987, DOI: 10.3878/j.issn.1006-9895.1987.01.09
Abstract: 1981—1983年在上海地区11个观测站进行了雨水pH值观测,取到资料2448份.从资料分析得到:(1)雨水pH值与天气背景有关,静止锋天气影响时,酸雨出现几率达44.5%,雨水较酸;暖锋天气时,酸雨出现几率仅9%.(2)台风、高压边缘天气影响下,酸雨的形成主要是受局地污染源的影响;但静止锋、冷锋、低压系统天气时,酸雨的形成不仅受局地污染源的影响,而且还可能受随气流输送来的外来污染物的影响.
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