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  • Hindawi Limited  (8)
  • Wang, Weiqiang  (8)
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  • Hindawi Limited  (8)
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  • 1
    Online Resource
    Online Resource
    Hindawi Limited ; 2017
    In:  Shock and Vibration Vol. 2017 ( 2017), p. 1-11
    In: Shock and Vibration, Hindawi Limited, Vol. 2017 ( 2017), p. 1-11
    Abstract: The fatigue damage of compressor blade steel KMN-I was investigated using nonlinear ultrasonic testing and the relation curve between the material nonlinearity parameter  β and the fatigue life was obtained. The results showed that the nonlinearity parameter increased first and then decreased with the increase of the fatigue cycles. The microstructures were observed by scanning electron microscopy (SEM). It was found that some small defects like holes and pits appeared in the material matrix with the increase of the fatigue cycles, and the nonlinearity parameter increased correspondingly. The nonlinearity parameter reached the peak value when the microcracks initiated, and the nonlinearity parameter began to decrease when the microcracks further propagated to macrocracks. Therefore, it is proved that the nonlinearity parameter can be used to characterize the initiation of microcracks at the early stage of fatigue, and a method of evaluating the fatigue life of materials by nonlinear ultrasonic testing is proposed.
    Type of Medium: Online Resource
    ISSN: 1070-9622 , 1875-9203
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2017
    detail.hit.zdb_id: 2070162-7
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  • 2
    In: Stem Cells International, Hindawi Limited, Vol. 2018 ( 2018-03-25), p. 1-9
    Abstract: With their properties of self-renewal and differentiation, embryonic stem (ES) cells hold great promises for regenerative therapy. However, teratoma formation and ethical concerns of ES cells may restrict their potential clinical applications. Currently, parthenogenetic embryonic stem (pES) cells have attracted the interest of researchers for its self-renewing and pluripotent differentiation while eliciting less ethic concerns. In this study, we established a model with ES and pES cells both stably transfected with a double-fusion reporter gene containing renilla luciferase (Rluc) and red fluorescent protein (RFP) to analyze the mechanisms of teratoma formation. Transgenic Vegfr2-luc mouse, which expresses firefly luciferase (Fluc) under the promoter of vascular endothelial growth factor receptor 2 ( Vegfr2-luc ), was used to trace the growth of new blood vessel recruited by transplanted cells. Bioluminescence imaging (BLI) of Rluc/Fluc provides an effective tool in estimating the growth and angiogenesis of teratoma in vivo. We found that the tumorigenesis and angiogenesis capacity of ES cells were higher than those of pES cells, in which VEGF/VEGFR2 signal pathway plays an important role. In conclusion, pES cells have the decreased potential of teratoma formation but meanwhile have similar differentiating capacity compared with ES cells. These data demonstrate that pES cells provide an alternative source for ES cells with the risk reduction of teratoma formation and without ethical controversy.
    Type of Medium: Online Resource
    ISSN: 1687-966X , 1687-9678
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2018
    detail.hit.zdb_id: 2573856-2
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  • 3
    Online Resource
    Online Resource
    Hindawi Limited ; 2021
    In:  International Journal of Energy Research Vol. 45, No. 15 ( 2021-12), p. 20949-20958
    In: International Journal of Energy Research, Hindawi Limited, Vol. 45, No. 15 ( 2021-12), p. 20949-20958
    Type of Medium: Online Resource
    ISSN: 0363-907X , 1099-114X
    URL: Issue
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2021
    detail.hit.zdb_id: 1480879-1
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  • 4
    Online Resource
    Online Resource
    Hindawi Limited ; 2017
    In:  International Journal of Chemical Engineering Vol. 2017 ( 2017), p. 1-8
    In: International Journal of Chemical Engineering, Hindawi Limited, Vol. 2017 ( 2017), p. 1-8
    Abstract: An annular gap nozzle was applied in solution enhanced dispersion by supercritical fluids (SEDS) process to prepare cefquinome controlled size submicron particles so as to enhance their efficacy. Analysis results of orthogonal experiments indicated that the concentration of solution was the primary factor to affect particle sizes in SEDS process, and feeding speed of solution, precipitation pressure, and precipitation temperature ranked second to fourth. Meanwhile, the optimal operating conditions were that solution concentration was 100 mg/mL, feeding speed was 9 mL/min, precipitation pressure was 10 MPa, and precipitation temperature was 316 K. The confirmatory experiment showed that D 50 of processed cefquinome particles in optimal operating conditions was 0.73  μ m. Moreover, univariate effect analysis showed that the cefquinome particle size increased with the increase of concentration of the solution or precipitation pressure but decreased with the increase of solution feeding speed. When precipitation temperature increased, the cefquinome particle size showed highest point. Moreover, characterization of processed cefquinome particles was analyzed by SEM, FT-IR, and XRD. Analysis results indicated that the surface appearance of processed cefquinome particles was flakes. The chemical structure of processed cefquinome particles was not changed, and the crystallinity of processed cefquinome particles was a little lower than that of raw cefquinome particles.
    Type of Medium: Online Resource
    ISSN: 1687-806X , 1687-8078
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2017
    detail.hit.zdb_id: 2448899-9
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  • 5
    Online Resource
    Online Resource
    Hindawi Limited ; 2021
    In:  International Journal of Energy Research Vol. 45, No. 5 ( 2021-04), p. 6958-6965
    In: International Journal of Energy Research, Hindawi Limited, Vol. 45, No. 5 ( 2021-04), p. 6958-6965
    Type of Medium: Online Resource
    ISSN: 0363-907X , 1099-114X
    URL: Issue
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2021
    detail.hit.zdb_id: 1480879-1
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  • 6
    Online Resource
    Online Resource
    Hindawi Limited ; 2021
    In:  Shock and Vibration Vol. 2021 ( 2021-2-4), p. 1-14
    In: Shock and Vibration, Hindawi Limited, Vol. 2021 ( 2021-2-4), p. 1-14
    Abstract: According to the new stress distribution pattern and the strong strata behaviors as the characteristics of the coal pillars in the close-distance multiseam coal pillar mining, the common characteristics of different types of overlying coal pillars were summarized and analyzed. Moreover, a theoretical model for the mechanism of strong strata behaviors in the close-distance multiseam coal pillar mining was established, which was validated by the monitoring data of seismic computed tomography CT, microseism, and electromagnetic radiation (EMR). Furthermore, the results of the study indicated that the main factors affecting the strong strata behaviors were the static stress concentration caused by the overlying coal pillars and the dynamic disturbance caused by the fracturing and slipping of the overlying coal pillars and roof under the influence of mining. In the case of Xinzhouyao coal mine, the transmitted stress and lateral support pressure of the overlying coal pillars accounted for 78.3% and 16% of the vertical concentrated stress, respectively, and the areas closer to the overlying coal pillars were more susceptible to dynamic load disturbances. The monitoring results of seismic computed tomography CT and EMR demonstrated the static load stress concentration area was distributed near the overlying coal pillar, and the stress concentration degree was greater in the area of superimposed lateral support pressure and advanced support pressure. Moreover, microseismic spatial positioning revealed that the high-energy microseismic events were mainly concentrated near the overlying large coal pillars and roof. The on-site multiparameter detection results were highly consistent with the characteristics of actual strata behaviors and the conclusions of the theoretical model. This method could provide a reference for the quantitative calculation of stress distribution under similar conditions and the identification of the danger zone of strata behaviors.
    Type of Medium: Online Resource
    ISSN: 1875-9203 , 1070-9622
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2021
    detail.hit.zdb_id: 2070162-7
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  • 7
    Online Resource
    Online Resource
    Hindawi Limited ; 2019
    In:  Mathematical Problems in Engineering Vol. 2019 ( 2019-03-11), p. 1-13
    In: Mathematical Problems in Engineering, Hindawi Limited, Vol. 2019 ( 2019-03-11), p. 1-13
    Abstract: The paper presents a mechanistic cutting force model of serrated end mill to predict cutting forces. Geometric model of serrated end mill is established, which covers variable helix end mill geometries. In this model, the serration of helical cutting flutes is expressed spatially and the wave of serration is defined to be a sine wave. The spatial vector is applied to define chip thickness so as to enhance the spatial expressiveness of the model, which is perpendicular to the curvature of each flute. Each helical flute is scatted into a series of infinitesimal cutting edges. The infinitesimal cutting forces depend on three cutting force coefficients and three edge force coefficients in the tangential, radial, and axial directions at every cutting element. By integrating the infinitesimal cutting forces along each cutting edge, the milling forces with serrated end mill can be predicted. The model feasibility of the serrated end mill is verified by comparing the predicted and measured cutting forces. Moreover, the model is also verified such that it can also predict cutting forces with other types of end mills, such as variable helix serrated end mill, variable helix end mill, and regular end mill.
    Type of Medium: Online Resource
    ISSN: 1024-123X , 1563-5147
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2019
    detail.hit.zdb_id: 2014442-8
    SSG: 11
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  • 8
    Online Resource
    Online Resource
    Hindawi Limited ; 2020
    In:  Advances in Materials Science and Engineering Vol. 2020 ( 2020-01-20), p. 1-15
    In: Advances in Materials Science and Engineering, Hindawi Limited, Vol. 2020 ( 2020-01-20), p. 1-15
    Abstract: The selective laser melting technique is widely used in aerospace and biomedical industries, and the performance of formed 316L parts is significantly subject to the forming angle. As the selective laser melting 316L parts are constrained by multiple performance indexes, the study involves multivariate interaction influenced on the forming parameters such as the angle with the xz plane, the angle with the xy plane, laser power, scan speed, powder thickness, and hatching space on the indexes like tensile strength, density, and surface roughness with linear regression equations based on multiobjective optimization to obtain the best process parameters. The study results of microstructure performance of the formed 316L parts show that the angle with the xz plane has significant effect on the experiment indexes, while the layer thickness has the greatest effect on the indexes. After stretching, the molten pools are obviously elongated and the microstructure of the formed 316L parts is composed of equiaxed crystals and columnar crystals with a grain width of 0.28–0.4 nm. The secondary growth of the dendrites is not obvious, and the crystallinity of the selective laser melting 316L parts is not as good as the standard parts, with the microstructure showing directional solidification due to grain refinement and microscopic distortion of crystals. As the fracture has dimples, it is a ductile fracture and typical plastic fracture. The hardness near the fracture is higher than that of the substrate, whilst the indexes regarding the selective laser melting parts are higher than the ASTM-A182 and ASTM-F3184-16 standards. Since the theoretical model built in this study has less error, the findings have practical engineering application value.
    Type of Medium: Online Resource
    ISSN: 1687-8434 , 1687-8442
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2020
    detail.hit.zdb_id: 2501025-6
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