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21.
22.
Molecular dynamic model of nanofluid between flat plates under shear flow conditions was built. The nanofluid model consisted
of 12 spherical copper nanoparticles with each particle diameter of 4 nm and argon atoms as base liquid. The Lennard–Jones
(LJ) potential function was adopted to deal with the interactions between atoms. Thus, the motion states of nanoparticles
during the process of flowing were obtained and the flow behaviors of nanofluid between flat plates at different moments could
be analyzed. The simulation results showed that an absorption layer of argon atoms existed surrounding each nanoparticle and
would accompany with the particle to move. The absorption layer contributed little to the flow of nanoparticles but much to
the heat transferring in nanofluids. Another phenomenon observed during shear flowing process was that the nanoparticles would
vibrate and rotate besides main flowing with liquid argon and these micro-motions could strengthen partial flowing in nanofluids. 相似文献
23.
Huan Xie Xin Luo Xiong Xu Haiyan Pan Xiaohua Tong 《International journal of remote sensing》2016,37(8):1826-1844
The successful launch of the Landsat 8 satellite continues the Earth observation of the Landsat series, which has been taking place for nearly 40 years. With the increase in the band number and the improved spectral range compared with the previous Landsat imagery, it will be possible to expand the application of the new Landsat 8 imagery. The purpose of this study is to explore water extraction based on the new Landsat 8 Operational Land Imager (OLI) imagery. According to the specific inland water conditions (clear water, turbid water, and eutrophic water), a number of highly adaptable water indices are assessed for water extraction using Landsat OLI imagery. The results show that clear water is the easiest to extract among the different types of waterbodies, with the highest average accuracy of 97%. The highest-accuracy methods are the automated water extraction index for shadow pixels (AWEIsh), the normalized difference water index using bands 4 and 7 (NDWI47), and the normalized difference water index using bands 3 and 7 (NDWI37), with accuracies of 98.55%, 95.50%, and 96.61%, corresponding to clear water, turbid water, and eutrophic water, respectively. Through the analysis of the different methods for optimal band selection, the seventh band OLI7 (shortwave infrared 2, SWIR-2) of Landsat OLI shows the best performance in water identification. When applying the water indices to water extraction, Otsu’s algorithm has been used to automatically select the water threshold. Using extensive experiments with Otsu’s algorithm and a manual method, it was found that Otsu’s algorithm can replace manual selection and has the ability to select an accurate threshold for water extraction. 相似文献
24.
Acoustic emission (AE) experiments have been performed on gas-saturated coal specimens under conventional triaxial compression. The AE characteristics were investigated for a methane gas flow through the coal specimen. One AE parameter, AE count, when normalized by the total count number was used to represent the damage evolution in the gassy coal. It is shown that this AE parameter is a reasonable indicator for damage occurring within the coal specimen since its envelope has almost the same shape as the complete stress–strain curve, except for a short time delay. In addition, the change in AE count is highly consistent with the change in coal permeability. Test results also show that methane containing coal emits a small number of AE events before entering the yield stage. AE activity gradually increases during the yield process up to the peak stress. The lowest permeability corresponds to the highest AE activity, implying failure will soon occur. An AE based constitutive model was constructed and the theoretical results agree well with those of experiments. 相似文献
25.
Xiaohua Zhou Shuren Zhang Ying Yuan Bo Li Jingsong Liu 《Journal of Materials Science: Materials in Electronics》2006,17(2):133-136
Nonreducible X7R dielectric materials, which can be cofired with Ni electrode, were obtained by doping nanometer additives
to BaTiO3 powders synthesized by employing a sol-gel method. The crystallization process, structure and constituent of nanometer additives,
as well as morphologies were studied via differential thermal and thermogravimetric analyses (DTA/TG), X-ray diffraction (XRD)
and transmission electron microscopy (TEM). The effects of the calcining temperature of dopants on the dielectric properties
were also discussed. The experiment results proved that higher-performance X7R dielectric materials could be obtained via
nanometer doping compared with conventional doping. At room temperature, dielectric constant is more than 3000; dielectric
loss lower than 1.0% and insulation resistance more than 1011Ω ⋅cm. 相似文献
26.
对医学常规体液检查中5种离子浓度的检测,利用单片机、高精度A/D芯片、实时时钟等,给出了一种切实可行的解决方案,并详细地阐述了系统的软硬件设计。 相似文献
27.
28.
王晓华 《辽宁石油化工大学学报》1997,(4)
在纤维缠绕压力容器设计中,纤维缠绕的方向及各方向纤维用量配比是关键问题。过去的研究中,这一问题一直没能得到很好地解决,特别是各方向纤维用量问题。本文在文献[1~4]的基础上,以加权因子和铺设角为参量给出了对称多层正交各向异性外压容器筒体失稳的最佳铺层理论值。得出了加权因子s取最佳值的范围为0<s<0.25的结论。文中算例表明,按最佳取值给出的临界压力较其它情况有较大幅度的提高。 相似文献
29.
基因方法是基于自然选择和自然基因机制的并行随机自适应工程模型参数全局优化估计的通用数值方法。它不限制模型结构、优化准则、被估参数的数目、约束条件等,已开始广泛用于各种工程模型的优化设计之中。文中对它的原理、步骤、特点进行初步探讨,并针对基因方法的弱点,作者提出予以改进的加速基因方法,后者在最大流量频率曲线参数估计中得到成功应用 相似文献
30.
张履康 《安徽冶金科技职业学院学报》2004,14(3):115-118
发展社会主义民主政治,建设社会主义政治文明是中国共产党务实的战略思维和历史唯物主义的发展观,反映了经济社会发展的内在求,揭示了人、社会和自然的和谐统一.社会主义政治文明进程本身也体现和反映出人类政治文明的认知性、实践性和过程性. 相似文献