Papers by Keyword: Infiltration

Abstract: Numerical modelling of unsaturated-saturated flow under centrifugation with moving arms is studied. A numerically efficient approximation is presented for mathematical model based on Richard's nonlinear and degenerate equation expressed in terms of effective saturation using Van Genuchten-Mualem ansatz with soil parameters in unsaturated zone. The method is suitable for determination of soil parameters via the solution of inverse problem in an iterative way. Using centrifuge offers significant time savings and provides us with many data for the parameter estimation. The present implementation of our method requires only very cheap measurements of global characteristics.

Abstract: For over a decade, metal foams have attracted a growing research interest because of the development of certain production processes. The advantages of metal foams most cited in the scientific literature are their low weight. However, one of the obstacles to their use on an industrial scale is the dispersion of their mechanical properties, in part because of their microstructural heterogeneity.

Abstract: La0.8Sr0.2FeO3 electrodes modified with nanoparticles of La0.8Sr0.2MnO3 (LSF/LSM) were prepared by infiltration method. LSM solution had good wettability on LSF surfaces and good electrochemical compatibility with LSF. The impedance of half-cells incorporating the electrodes was also examined. The deconvolution of the impedance spectrum indicated that the peak positions are changed after the LSF infiltration. The LSF/LSM electrode exhibited smaller polarization resistance than pure LSF electrode. Finally, a transform from asymmetry to symmetry appeared in the polarization curves of LSF/LSM electrode with the increase of temperature.

Abstract: The Heifangtai plateau, having an area of about 14 km2, has experienced more than 70 loess landslides since 1960s. Aiming at investigating the slope instability induced by irrigation, a field test was proposed. As an important part of the field test, a detailed site investigation was conducted systematically. The topographical details of a typical loess slope at Heifangtai were obtained by a 3D laser scanner. The cracks and the plan view of the site were obtained using GPS. The lithological profile, groundwater level, sampling and soil permeability, were also investigated respectively. On the basis of the site investigation, the field test was conducted successfully.

Abstract: A surface alloyed process that adopted ferrous-tungsten and carbon powders as reactants to in-suite synthesize WC reinforcement particles with the assistance of molten carbon steel was attempted in this paper. Results showed that the surface alloyed layer is dense and there are no obvious defects. Microstructures from surface to core are consisted of three different layers, i.e., the top surface alloyed layer, the interim transitional layer and the bottom matrix steel. There are no any WC particles formed in the surface alloyed layer which is consisted of dendrite matrix and inter-dendritical net eutectics and carbides. The net carbides have two types: one is WC or W2C; the other is M7C3. Few large metal tungsten particles are distributed at part bottom of the surface alloyed layer. The microstructure in the transitional layer is consisted of large amounts of pearlites and certain amounts of net carbides.

Abstract: Waterlogged land characterized by low productivity impact the productivity of the adjacent land and increase soil erosion. Gangzhongwa, one type of waterlogged lands, is widely distributed in Jiusan cultivated lands in Heilongjiang province China. Observation of soil profiles and measurements of soil physical properties were carried to investigate the factors related to the waterlogged land formation. The results showed Gangzhongwa waterlogged land is formed due to three reasons: firstly, the water table of groundwater is shallow and the soil profile texture varies regularly from clay loam layer, and sandy loam layer to aquitard layer; secondly soil infiltration is significantly correlated with sand content and gravel content; and thirdly the subsurface runoff makes the soil profile saturated where the surface clay loam layer is thin but the sandy layer is thick with larger infiltration rates. This study presents some theoretical insights for the Gangzhongwa waterlogged land conservation plan.

Abstract: Increasing impermeable surface area has become a serious burden for drainage of urban stormwater. It is thus important to know how much surface runoff may be generated by storms of varying intensity and duration, especially on a continual daily basis. In this paper, the field hydrology model-DRAINMOD was used to simulate daily surface runoff under different surface condition in Xi’an, China. As a major hydrological components in DRAINMOD, daily evapotranspirations were calculated with the FAO Penman-Monteith method and read into the model. Infiltration parameters were considered as calibration factors in the modeling process. Available data from a local rainfall-runoff experiment were used for model calibration by matching the model predicted surface runoff with the measured values on an event basis. The calibrated model was then used for long term simulations in order to examine the impact of varying climatic conditions and land cover on urban runoff. The modeling results may provide a practical guidance for city storm water management.

Abstract: Compacts made of sintered diamond powder (DP) are not only extensively used but also essential cutting inserts for operations such as machining metal components or drilling rocks for petroleum extraction. The high pressure and high temperature (HPHT) sintering can be achieved either by an initial mixture of DP with a metallic binder or by first processing the DP at HPHT, which creates a sintered skeleton, followed by the molten metallic binder infiltration. This work investigates the infiltration of Cu, Co and Ni, as binders, into sintered diamond powders with different particles size. It was found that migration of the liquid phase through the sintered diamond skeleton complies with the Darci Law. The penetration coefficient varied from 0.89 x 10^-7 to 6.41 x 10^-7 μm² indicating that the migration is affected by several factors.

Abstract: The paper presents the basics information about manufacturing and selected properties of composite with aluminium alloy matrix containing glassy carbon as a solid lubricant. The so far used method based on mixing the prepared glassy carbon particles with a liquid metal matrix, has been compared with a new method elaborated by the authors of the article. With this novel method carbon is introduced into a composite with the application of liquid carbon precursor and porous ceramic foams. It is then followed by precursor pyrolysis where, as the result, glassy carbon is obtained. Ceramic foams help liquid precursor penetrate the ceramic spheroid pores by forming a thin film of glassy carbon on their walls. The composite produced in such a way features uniform distribution of carbon within its entire volume which significantly improves tribological properties of the composite. Costly mixing procedure is not needed. Sliding friction coefficient of the new composite against cast iron (µ = 0.06-0.28 at wearing in and 0,12 after wearing in) is much lower than in case of composite containing only ceramic foam as a reinforcing phase (μ = 0.25-0.32).

Abstract: The hydrological effect of frozen soil is a particular hydrological phenomenon in frozen regions, which mainly performs in three aspects as following: (a) The poor permeability or impermeability of the frozen soil changes the infiltration and evapotranspiration process in soil and affects the storage and thawing process. (b) Frozen soil changes annual and inter-annual runoff variation process in a watershed. (c) Frozen soil influences and regulates the global climate. Based on the analysis of the frozen soil effects on the evaporation, infiltration and runoff in current research, this paper systematically analyzed relative researches on hydrological effects of frozen soil in recent years from environmental characteristics, data sources, research methods and major conclusions. The main conclusions are as follow: In China, research on hydrological effects of frozen soil started relatively late and developed slowly; There are few initial research on frozen soil hydrology and most research concerning which has been focused on the mechanics of frozen soil engineering rather than the discussions on hydrology; Future development of frozen soil hydrology in should be strengthened in some other aspects. Research on hydrological effects of frozen soil can lead to better understanding of this exceptional hydrological process, which has great significance on utilization of water resources and ecological environment protection in cold regions.