Motion of a system of seismic sources over ice on a body of water under the action of a pulse

The vertical motion of a system of two identical seismic sources and a spring truck tractor on ice under the action of a shock pulse from the seismic sources is studied to estimate the strength of ice. It is shown that during the pulse time, the interaction of the masses of the seismic sources and the tractor is small and the compressibility effect of the liquid can be ignored. Calculations show that for the seismic sources, the dynamic load far exceeds the static load and for the tractor, the static load is maximal. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 147–155, March–April, 2007.     

Role of nonlocal exchange in molecular crystals: The case of two proton‐ordered phases of ice

We present a periodic density functional theory investigation of twoproton‐ordered phases of ice. Their equilibrium lattice parameters,relative stabilities, formation energies, and densities of states havebeen evaluated. Nine exchange‐correlation functionals, representativeof the generalized gradient approximation (GGA), global hybrids,range‐separated hybrids, meta‐GGA, and hybrid meta‐GGA families havebeen taken into account, considering two oxygen basis sets. Althoughthe hydrogen‐bond network of ice is well reproduced at the B3LYP,M06‐L, or LC‐ wPBE levels, formation energies are only correctlyevaluated with the two former functionals. Band gaps on the other handare only quantitatively reproduced at the B3LYP level. These resultsindicate that this last functional, a de facto reference formolecular calculations, gives in average the most accurate results forthe considered ice properties. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

The superhydrophobicity of polymer surfaces: Recent developments

Superhydrophobicity is the extreme water repellence of highly textured surfaces. The field of superhydrophobicity research has reached a stage where huge numbers of candidate treatments have been proposed and jumps have been made in theoretically describing them. There now seems to be a move to more practical concerns and to considering the demands of individual applications instead of more general cases. With these developments, polymeric surfaces with their huge variety of properties have come to the fore and are fast becoming the material of choice for designing, developing, and producing superhydrophobic surfaces. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1203–1217, 2011     

Numerical methods for a fixed domain formulation of the glacier profile problem with alternative boundary conditions

In this paper we develop a set of numerical techniques for the simulation of the profile evolution of a valley glacier in the framework of isothermal shallow ice approximation models. The different mathematical formulations are given in terms of a highly nonlinear parabolic equation. A first nonlinearity comes from the free boundary problem associated with the unknown basal extension of the glacier region. This feature is treated using a fixed domain complementarity formulation which is solved numerically by a duality method. The nonlinear diffusive term is explicitly treated in the time marching scheme. A convection dominated problem arises, so a characteristic scheme is proposed for the time discretization, while piecewise linear finite elements are used for the spatial discretization. The presence of infinite slopes in polar regimes motivates an alternative formulation based on a prescribed flux boundary condition at the head of the glacier instead a homogeneous Dirichlet one. Finally, several numerical examples illustrate the performance of the proposed methods.     

基于亮度均衡化的图像阈值分割技术在黄河冰凌监测中的应用

一种基于亮度均衡化的图像阈值分割算法被提出.该算法将冰凌图像亮度数据均衡化,以类间方差最大为标准,求得最佳阈值,并将冰凌图像转化为二值图像,通过冰凌像素统计,最终确定冰凌密度.该算法被应用于黄河河道冰凌图像密度的计算中,取得较好的效果.     

Energy losses of ice slurry in pipe sudden contractions

The paper presents the results of the experimental research on the ice slurry loss coefficient during its flow through sudden contractions. Experimental studies were conducted using a few of the most common contractions of copper pipes. Six contraction ratios were covered: 0.500, 0.615, 0.650, 0.769, 0.800 and 0.813. In the experimental research, the mass fraction of solid particles in the slurry ranged from 20 to 30 (20%, 25%, 30%). Research results allow for determining the theoretical correlation for the ice slurry, in order to calculate the loss coefficient in contractions during laminar flow. The results of experimental investigations also confirmed that the loss coefficients in contractions in turbulent (transitional) flow of the ice slurry are the same as in the case of Newtonian liquids. The paper also presents original theoretical correlation for calculating the kinetic energy correction factor in the laminar range flow of liquid in the Bingham model. This correlation is used in this work for calculation of the ice slurry flow through contractions.     

人造柱状冰特性的研究

由于地形的变化,冰特性的研究对研究冰川、河、湖、海冰的动力过程以及破冰均有重要意义.本文对人造柱状冰的特性进行研究和分析,给出了人造柱状冰的制备过程和利用压力试验机对人造冰特性进行的测定,主要包括冰冻模具的制作、冰试样的制备和加工以及对于纯水冰柱和含沙冰柱的特性研究.在冰柱的冰冻温度为-10℃、-20℃、-30℃和-4...     

High P–T Brillouin scattering study of H2O melting to 26 GPa

The properties of solid and liquid phases of H₂O at high pressure and temperature remain an active area of research. In this study, Brillouin spectroscopy has been used to determine the temperature dependence of sound velocities in H₂O as a function of pressure up to 26 GPa through the phase field of ice VII and into the liquid to a maximum temperature of 1200 K. The Brillouin shift of the quasi-longitudinal acoustic mode moves to lower frequencies upon melting at each pressure. As a test of the method, measurements of the melting of Ar by Brillouin scattering at several pressures show a similar behavior for the acoustic mode, and measured melting points are consistent with previous results. The results of H₂O melting are consistent with previously reported melting curves below 20 GPa. The data at higher pressure indicate that ice melts at a higher temperature than a number of previous studies have indicated.     

醋酸甲羟孕酮与β-环糊精包络作用的光谱研究及应用

用紫外吸收、荧光光谱法对水溶液中β－环糊精（β－ＣＤ）与醋酸甲羟孕酮（ＭＡ）主客体包络物的光谱行为进行了研究．利用改进的Ｂｅｎｅｓｉ－Ｈｉｌｄｅｂｒａｎｄ法测定了包络物的形成常数，初步探讨了某些水溶性一元醇的引入对该包络物形成及荧光性质的影响，并提出了测定ＭＡ的高灵敏度荧光光度新方法，方法的最低检出限为８．９×１０－９ｍｏｌ·Ｌ－１．用该法测定样品中ＭＡ的结果令人满意，回收率为９７．９％～１０１．７％，平均回收率为９９．９％（ｎ＝５）