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991.
M. Yanuka 《Transport in Porous Media》1992,7(3):265-282
The percolation theory approach to static and dynamic properties of the single- and two-phase fluid flow in porous media is described. Using percolation cluster scaling laws, one can obtain functional relations between the saturation fraction of a given phase and the capillary pressure, the relative permeability, and the dispersion coefficient, in drainage and imbibition processes. In addition, the scale dependency of the transport coefficient is shown to be an outcome of the fractal nature of pore space and of the random flow pattern of the fluids or contaminant. 相似文献
992.
J. Magnaudet 《Applied Scientific Research》1993,51(1-2):525-531
In this paper we propose a new rational model for turbulent transport of Reynolds stresses and dissipation. For this purpose we first analyse some properties of diffused turbulence i.e. turbulence where dissipation is balanced by turbulent diffusion arising from inhomogeneity. Then we use some of these results to deduce some mathematical requirements that must be satisfied by any rational model and we show that they are not verified by available models. Consequently we derive a more general model taking into account the various properties of diffused turbulence. 相似文献
993.
Kabita Chakrabarty Prabirkumar Saha Aloke Kumar Ghoshal 《Journal of membrane science》2010,346(1):37-44
This paper presents an experimental investigation on facilitated and simultaneous transport of mercury and lignosulfonate (LS) through a flat sheet supported liquid membrane (SLM) having Nylon 6,6 as support, trioctylamine (TOA) as carrier and dichloroethane as solvent. The experiments were performed at various operating conditions such as strip phase concentration, feed pH, carrier concentration and feed concentration to find the best set of parameters that would yield the maximum separation of pure mercury as well as its mixture with LS. The experiments were performed in co-transport mode using NaOH as the strip phase. It was observed that extraction of mercury as well as its mixture increases with increase in concentration of NaOH up to a certain limit 0.1 M NaOH in case of pure solution and 0.2 M NaOH in case of mixture). Feed phase pH significantly affects the mercury separation process. However, initial feed concentration does not affect the extraction process appreciably. Separation of mixture of mercury and LS behaves in a similar way as their pure solution; however the extraction is low in comparison to pure solution. The extraction of mercury from its pure solution is about 81% in 1 h. The extraction of mercury and LS from their mixture is about 52.6% and 50.2%, respectively at optimum condition and in a period of 2 h. 相似文献
994.
Marcos R. Guilherme André R. Fajardo Marcos H. Kunita Adley F. Rubira 《European Polymer Journal》2010,46(7):1465-437
Nanocomposite hydrogel consisting of dispersed montmorillonite-crosslinked maltodextrin-co-dimethylacrylamide (malt-dex-co-DMAAm) as a highly stable device was developed. Carbon-carbon π-bonds issued from glycidyl methacrylate (GMA) were incorporated onto both the MMT (MMT-π) and the malt-dex (malt-dex-π) structures. The nanocomposite copolymer hydrogel was processed via radical crosslinking reaction of malt-dex-π with MMT-π in the presence of DMAAm. The radical reaction of the carbon-carbon π-bonds at the MMT-π was verified by treating the MMT-π with sodium persulfate. There was an excellent dispersion of the MMT-π at the interior of the matrix even after the nanocomposite hydrogel being swollen, demonstrating that the developed methodology can imprint stability of mineral nanoparticles into a porous polymer network preventing diffusion of water-bonded silicate platelets toward the outside matrix. The water absorption profile became more dependent on the polymer relaxation for mineral-loader nanocomposite hydrogels. Higher water absorption had an impact on reduction of elasticity modulus due to softer polymer network in swollen state. 相似文献
995.
We present a theoretical and numerical modeling study of the multiphysicochemical process in electrokinetic transport in silica nanochannels. The electrochemical boundary condition is solved by considering both the chemical equilibrium on solid-liquid interfaces and the salt concentration enrichment caused by the double layer interaction. The transport behavior is modeled numerically by solving the governing equations using the lattice Poisson-Boltzmann method. The framework is validated by good agreements with the experimental data for all range of ionic concentrations. The modeling results suggest that when the double layers interact, the bulk salt concentration enrichment results in the saturation of conductances for low ionic concentrations. Both the streaming conductance and the electrical conductance are enhanced by the double layer interaction, and such enhancements diminish when the channel size is larger than 10 times of the Debye length. The streaming conductance increases with pH almost linearly when pH < 8, while the electrical conductance increases with pH exponentially. 相似文献
996.
The thermoelectric properties of Pb0.5Sn0.5Te doped with In at 1.0, 2.0, and 3.0×1019/cm3 and sintered at a high pressure and high temperature (HPHT) of 4.0 GPa and 800 or 900 °C, respectively, have been studied. All samples show p-type semiconducting behavior with positive thermopower. We find that HPHT sintering of conventionally synthesized materials improves their thermoelectric properties. The highest power factor is obtained for In doping of 2.0×1019/cm3 with 13.5 μW/cm K2 at 230 °C. The corresponding figure of merit is 1.43×10−3/K. This represents a twofold improvement in thermoelectric figure of merit, compared to the conventionally sintered materials reported in the literature. When exposed to 400 °C for 10 days, samples sintered at 900 °C exhibit more stable thermoelectric properties, while the properties of those sintered at 800 °C deteriorated. These results demonstrate that HPHT sintering is a viable and controllable way of tuning the thermoelectric properties of PbTe-based materials. 相似文献
997.
FU S.Joshua 《中国科学:化学》2010,(5)
Black carbon(BC) and PM10 in the center of the Taklimakan Desert were online monitored in the whole year of 2007.In addi-tion,TSP samples were also synchronously daily collected by medium-volume samplers with Whatman41 filters in the spring of 2007.BC in the dust aerosol was up to 1.14%of the total mass of PM10.A remarkable seasonal variation of BC in the aerosol was observed in the order of winter>spring>autumn>summer.The peak value of BC appeared at midnight while the lowest one in the evening each day,w... 相似文献
998.
Single‐layer graphene has received much attention because of its unique two‐dimensional crystal structure and properties. In this review, we focus on the graphene devices in solution, and their properties that are relevant to chemical and biological applications. We will discuss their charge transport, controlled by electrochemical gates, interfacial and quantum capacitance, charged impurities, and surface potential distribution. The sensitive dependence of graphene charge transport on the surrounding environment points to their potential applications as ultrasensitive chemical sensors and biosensors. The interfacial and quantum capacitance studies are directly relevant to the on‐going effort of creating graphene‐based ultracapacitors for energy storage. 相似文献
999.
1000.
利用Mann迭代技巧,讨论了一类随机算子方程A(ω,x(ω),x(ω))=B(ω,x(ω))的随机解的存在唯一性,并给出了迭代序列收敛于解的误差估计,所得结果是某些已知结果本质改进和推广. 相似文献