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991.
Hirofumi?Arima Masanori?MondeEmail author Yuhichi?Mitsutake 《Heat and Mass Transfer》2003,39(7):535-543
The nonazeotropic binary mixtures such as, methanol/water, ethanol/water and ammonia/water, have variable boiling and dew
points, depending on the combination of substance and those mass fraction. It is expected to have a higher performance as
a result of decreasing the thermodynamically irreversible loss, when there is a relevant mass fraction. Therefore, ammonia/water
mixture is expected to use as working fluid in small temperature difference power generation cycles and absorption refrigeration
cycles. However, few experiments were carried out for measuring heat transfer coefficient for ammonia/water mixture in the
world.
An experimental study has been carried out to measure boiling heat transfer coefficient of an ammonia/water mixture on a horizontal
heated surface at low pressure of 0.2, 0.4 and 0.7 MPa and at low mass fraction of 0 < C < 0.27 and at high pressure 0.7, 1.0 and 1.5 MPa and at mass fraction of 0.5 < C < 1.0 and at heat flux under critical heat flux the heat transfer coefficient are compared with existing correlations prediction
and a revised correlation can be proposed to predict them well. 相似文献
992.
The results of calculating the shock wave structure in Ne–Ar, He–Ar, He–Ne, and He–Xe mixtures by means of the relaxation method on the basis of the system of Navier-Stokes equations and complete and modified systems of Burnett equations are compared with the results of direct statistical simulation (Monte-Carlo method). The domain of applicability of these systems of equations for calculating gas dynamic variable profiles is analyzed as a function of both the molecular mass ratio and the initialconcentrations. 相似文献
993.
994.
Theoretical analysis and numerical modeling of unidirectional fibrous micro- and nanocomposites carried out based on the theory of two-component mixture testify that the second mode of a transverse wave propagating along and polarized across the fibers may produce, at high frequencies, a kinematical pattern critical for the strength of the composite material. While the wave propagates, the components (matrix and fibers) of the mixture oscillate in antiphase. This fact may be critical because such oscillations generate forces separating the matrix and fibers, which is typical for the delamination of composite materials.Translated from Prikladnaya Mekhanika, Vol. 40, No. 10, pp. 78–87, October 2004. 相似文献
995.
996.
Inside Cover: Functionalized Graphene as a Gatekeeper for Chiral Molecules: An Alternative Concept for Chiral Separation (Angew. Chem. Int. Ed. 37/2014) 下载免费PDF全文
997.
为了提高动态手势检测的精确度,本文将基于YCbCr颜色空间的混合高斯背景建模应用于动态手势识别中,并且提出手势阴影消除的有效算法。首先,对待检测视频帧通过抠图抠出手势图像,在YCb'Cr'颜色空间进行椭圆拟合,统计建立椭圆肤色模型,继而在YCbCr颜色空间进行混合高斯背景建模检测出动态手势,点乘原图像得到含有阴影的RGB手势图像,对检测出的含有阴影的手势图像利用已建立的椭圆肤色模型进行阴影消除,最后将手势图像连成视频序列。实验结果表明,该算法在复杂背景下进行动态手势的检测率可达91.4%,高出传统方法10%左右,能够满足动态手势检测基本要求,且具有较高的实用价值。 相似文献
998.
《Particuology》2022
The strain characteristic and load transmission of mixed granular matter are different from those of homogeneous granular matter. Cyclic loading renders the mechanical behaviours of mixed granular matter more complex. To investigate the dynamic responses of gravel–sand mixtures, the discrete element method (DEM) was used to simulate the cyclic loading of gravel–sand mixtures with low fines contents. Macroscopically, the evolution of the axial strain and volumetric strain was investigated. Mesoscopically, the coordination number and contact force anisotropy were studied, and the evolution of strong and weak contacts was explored from two dimensions of loading time and local space. The simulation results show that increasing fines content can accelerate the development of the axial strain and volumetric strain but has little effect on the evolution of contact forces. Strong contacts tend to develop along the loading boundary, presenting the spatial difference. Weak contacts are firstly controlled by confining pressure and then controlled by axial stress, while strong contacts are mainly controlled by axial stress throughout the whole cyclic loading. Once compression failure occurs, the release of axial stress causes the reduction of strong contact proportion in all local regions. These findings are helpful to understand the dynamic responses of gravel–sand mixtures, especially in deformation behaviours and the Spatio-temporal evolution of contact forces. 相似文献
999.
《Particuology》2022
In this study, an inverse-problem method was applied to estimate the solid concentration in a solid–liquid two-phase flow. An algebraic slip mixture model was introduced to solve the forward problem of solid–liquid convective heat transfer. The time-average conservation equations of mass, momentum, energy, as well as the volume fraction equation were computed in a computational fluid dynamics (CFD) simulation. The solid concentration in the CFD model was controlled using an external program that included the inversion iteration, and an optimal estimation was performed via experimental measurements. Experiments using a fly-ash–water mixture and sand–water mixture with different solid concentrations in a horizontal pipeline were conducted to verify the accuracy of the inverse-problem method. The estimated results were rectified using a method based on the relationship between the estimated results and estimation error; consequently, the accuracy of the corrected inversion results improved significantly. After a verification through experiments, the inverse-problem method was concluded to be feasible for predicting the solid concentration, as the estimation error of the corrected results was within 7% for all experimental samples for a solid concentration of less than 50%. The inverse-problem method is expected to provide accurate predictions of the solid concentration in solid–liquid two-phase flow systems. 相似文献
1000.
Tail order of copulas can be used to describe the strength of dependence in the tails of a joint distribution. When the value of tail order is larger than the dimension, it may lead to tail negative dependence. First, we prove results on conditions that lead to tail negative dependence for Archimedean copulas. Using the conditions, we construct new parametric copula families that possess upper tail negative dependence. Among them, a copula based on a scale mixture with a generalized gamma random variable (GGS copula) is useful for modeling asymmetric tail negative dependence. We propose mixed copula regression based on the GGS copula for aggregate loss modeling of a medical expenditure panel survey dataset. For this dataset, we find that there exists upper tail negative dependence between loss frequency and loss severity, and the introduction of tail negative dependence structures significantly improves the aggregate loss modeling. 相似文献