地下水低渗透区重非水相液体(DNAPL)的增渗增移技术综述

重非水相液体(DNAPL)是一种物化性质稳定且毒性较强的有机污染物,对人类健康和生态环境存在极大威胁。由于其密度较大、穿透性强,DNAPL渗入地下后易在低渗透区积聚,形成长期污染源。低渗透区流速慢、传质难的特点使得常用地下水污染修复技术难以奏效,而目前针对该问题的系统性研究尚显不足,因此亟需梳理并总结通过增渗增移DNAPL实现低渗透区污染增效修复的方法,为后续研究提供一定参考价值。本文首先通过控制方程描述了增渗增移的原理;其次综述了两种分别以表面活性剂和电动为核心的增渗增移方法:表面活性剂通过胶束增溶和降低吸附实现增渗增移,电动则通过电渗和电迁移增移DNAPL;同时介绍了实际应用中耦合其他技术的案例,总结优缺点;最后对DNAPL未来的发展方向进行了展望。

崩落法放矿过程中充填体细颗粒运移特征研究

由于选厂搬迁,程潮铁矿西区保安矿柱由充填法转为崩落法开采,原充填体人工矿柱在崩落法开采过程中易产生粒化,导致矿石贫化,因此,亟需开展崩落法放矿过程中充填体细颗粒运移规律研究,为崩落法开采工艺参数确定提供理论支撑。利用PFC3D离散元软件制定充填体细颗粒运移初步试验与全面实验方案,对放矿过程中不同块度充填体细颗粒在矿石覆盖层中的渗移过程进行模拟,并开展不同放矿时期细颗粒运移特征研究。研究结果表明:①块度在0.3~0.7 m的充填体在放矿过程中更容易发生细颗粒渗移,造成矿岩覆盖层的混杂;②覆盖层散体与充填体的块度均对细颗粒渗移有显著影响,覆盖层散体块度的影响是高度显著的;③不同放矿时期细颗粒的运移方式有显著不同,且细颗粒的速度与其所处的相对位置有关。在此研究基础上建议将采场上方的矿石隔离层进行诱导冒落,合理控制其块度以减少细颗粒渗移现象的发生。

Penetrative and migratory behavior of alkali metal in different binder based TiB_2-C composite cathodes

In electrolyte melts containing K at low temperature, the penetrative and migratory path of alkali metals （K and Na） in pitch, furan, phenolic aldehyde and epoxy based TiB2-C composite cathodes during the electrolysis process were studied by EDS and self-made modified Rapoport apparatus. The electrolysis expansion rates, the diffusion coefficients of the alkali metals and the corrosion rates of the composite cathode were also calculated and discussed. The results show that no matter what kind of binder is used, alkali metals have the same penetrative path in composite cathodes：firstly in pore, then in binder and finally in carbonaceous aggregates. K and Na penetrate into both binder and carbonaceous aggregates, which leads to the expansion of composite cathodes, and K has stronger penetration ability than Na. Electrolysis expansion rate of resin based composite cathode is smaller than that of pitch based composite cathodes, and so do the diffusion coefficient and corrosion rate. Resin based composite cathode has better resistance ability to the penetration of alkali metals than pith based composite cathode, and phenolic aldehyde based composite cathode exhibits the strongest resistance ability. The penetration rate, the diffusion coefficient of alkali metals in phenolic aldehyde based TiB2-C composite cathode and the corresponding corrosion rate are 4.72 mm/h, 2.24×10^-5 cm^2/s and 2.31 mm/a, respectively.

有关拼色服装色牢度控制的探讨

分析了拼色服装存在的沾色问题及其原因,再结合当前色牢度指标考核的局限性,提出了拼色服装色牢度指标单独考核的必要性。

Management of biliary complications after orthotopic liver transplantation:The role of endoscopy

Biliary complications are signifi cant causes of morbidity and mortality after orthotopic liver transplantation (OLT). The estimated incidence of biliary complications after OLT ranges between 10%-25%,however,these numbers continue to decline due to improvement in surgical techniques. The most common biliary complications are strictures (both anastomotic and non-anastomotic) and bile leaks. Most of these problems can be appropriately managed with endoscopic retrograde colangiography (ERC). Other complications such as bile duct stones,bile casts,sphincter of Oddi dysfunction,and hemobilia,are less frequent and also can be managed with ERC. This article will review the risk factors,diagnosis,and endoscopic management of the most common biliary complications after OLT.

Prediction of ground surface displacement caused by grouting

Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contraction. A prediction method of ground surface displacement was developed. The reliability of the presented method was validated through a comparison between theoretical results and results from engineering practice. Results show that the present method is effective. The effect of parameters on uplift displacement was illustrated under different grouting conditions. Through analysis, it can be known that the ground surface uplift is mainly caused by osmosis of slurry and the primary influence angle of stratum β determines the influence range of surface uplift. Besides, the results show that ground surface uplift displacement decreases notably with increasing depth of the grouting cavity but it increases with increasing diffusion radius of grout and increasing grouting pressure.

3D numerical simulation of boreholes for gas drainage based on the pore–fracture dual media

A gas migration controlling equation was formulated based on the characteristics of the dual pore–fracture media of coal mass and in consideration of the matrix exchange between pores and fractures.A model of permeability dynamic evolution was established by analyzing the variation in effective stress during gas drainage and the action mechanism of the effect of coal matrix desorption on porosity and fracture in the coal body.A coupling model can then be obtained to characterize gas compressibility and coal deformability under the gas–solid coupling of loading coal.In addition,a 3D model of boreholes was established and solved for gas drainage based on the relevant physical parameters of real mines.The comparison and analysis results for the law of gas migration and the evolution of coal body permeability around the boreholes before and after gas extraction between the dual media and the single-seepage field models can provide a theoretical basis for further research on the action mechanism of gas drainage.

Time-Dependent Sediment Transport Subjected to Downward Seepage

Experiments were conducted using cohesionless sand particles with median diameter of 0.48 mm to investigate the time variation of sediment transport rate under the influence of local downward seepage.The experimental results show that the bedload transport rate in terms of volumetric sediment transport rate per unit width increased rapidly with time in the presence of suction,eventually reaching a peak beyond which it started to decrease.The trend of reduction was significantly reduced beyond 8 400 s after the test started.The analytical expression was derived in terms of dimensionless sediment transport rate and dimensionless time.The hypothesized relationships were compared with the experimental data,indicating a good agreement with each other.

Analytical solution of coal-bed methane migration with slippage effects in hypotonic reservoir

Using theoretical analysis, the single-phase gas seepage mathematical model influenced by slippage effects was established. The results show that the pressure of producing wells attenuates more violently than the wells without slippage effects. The decay rate of reservoir pressure is more violent as the Klinkenherg factor increases. The gas prediction output gradually increases as the Klinenberg factor increases when considering gas slippage effects. Through specific examples, analyzed the law of stope pore pressure and gas output forecast changing in a hypotonic reservoir with slippage effects. The results have great theoretical significance in the study of the law of coal-bed methane migration in hypotonic reservoirs and for the exploitation of coal-bed methane.

A Dynamic Model for Simulating Atmospheric, Surface and Soil Water interactions in Hillslope of Loess Area Under Natural Conditions and Its Application

The mechanism of atmospheric, surface and soil water interactions (water transformation) in hillslope under natural conditions was analyzed, and a dynamic model was developed to simulate infiltration, overland flow and soil water movement during natural rainfall in hillslope, by bringing forward concepts such. as rainfall intensity on slope and a correction coefficient of saturated soil water content for soil surface seal. Some factors, including slope angle, slope orientation and raindrop inclination, which affect the rainfall amount on slope, were taken into account while developing the dynamic model. The effect of surface seal on infiltration and water balance under a boundary condition of the second kind was also considered. Application of the model in a field experiment showed that the model simulated precisely the infiltration, overland flow and soil water movement in hillslope under natural rainfall conditions.

二次运移数学模型及其在鄂尔多斯盆地陇东地区长8段石油运移研究中的应用

建立在物理实验基础上的数学模拟技术正成为油气运移研究的重要手段.基于油气趋向于沿着范围狭窄的优势路径发生运移的认识,利用渗逾理论建立油气运聚数学模型,厘定模型在不同运移实验条件下的适用性;进而通过模拟分析,讨论大尺度宏观均匀输导层内运移路径的特征.最后以鄂尔多斯盆地陇东地区三叠系延长统长8油层段的运移研究为例,分析盆地尺度油气运移路径特征.获得油气在非均匀输导条件下形成优势运移路径的认识:流体势的空间变化决定了石油二次运移的主要方向,输导层的非均质性控制着油气二次运移路径的特征及形态.

Parametric Study by Dynamic Simulation of the Influence of the Air Infiltration Rate and the Convective Thermal Transfer Coefficient on the Thermal Behavior of Residential Buildings Built with Cut Lateritic Blocks

Sustainable building design in dry tropical areas recommends reducing exposure of buildings to solar radiation and/or designing efficient enclosures with satisfactory thermal inertia.We propose in this paper a study of the influence of the infiltration rate in the building and the coefficient of thermal transfer by convection of the walls, on the thermal comfort using TRNSYS software. All the models carried out were validated by recognized scientific criteria, namely correlation （R） and determination （R2） coefficients on the one hand and NBME and CVRMSE coefficients defined by ASHARE, 2002 on the other hand. The results obtained indicate that the modulation of the air infiltration rate allows the simulations on TRNSYS to be compared to in-situ measurements, with an annual average relative difference of 2.86% on the temperature difference. Furthermore, depending on the parameterization of the heat transfer coefficients by convection of the internal and external walls of walls used in the STD, the average annual difference can be reduced by 1% to 4% between the predictions and the measurements.

Experimental investigation on rainfall infiltration and solute transport in layered porous and fractured media

Layered structures with upper porous and lower fractured media are widely distributed in the world. An experimen- tal investigation on rainfall infiltration and solute transport in such layered structures can provide the necessary foundation for effectively preventing and forecasting water bursting in mines, controlling contamination of mine water, and accomplishing ecological restoration of mining areas. A typical physical model of the layered structures with porous and fractured media was created in this study. Then rainfall infiltration experiments were conducted after salt solution was sprayed on the surface of the layered structure. The volumetric water content and concentration of chlorine ions at different specified positions along the profile of the experiment system were measured in real-time. The experimental results showed that the lower fractured media, with a considerably higher permeability than that of the upper porous media, had significant effects on preventing water infil- tration. Moreover, although the porous media were homogeneous statistically in the whole domain, spatial variations in the features of effluent concentrations with regards to time, or so called breakthrough curves, at various sampling points located at the horizontal plane in the porous media near the porous-fractured interface were observed, indicating the diversity of solute transport at small scales. Furthermore, the breakthrough curves of the outflow at the bottom, located beneath the underlying fractured rock, were able to capture and integrate features of the breakthrough curves of both the upper porous and fractured media, which exhibited multiple peaks, while the peak values were reduced one by one with time.

Extended adsorption transport models for permeation of copper ions through nanocomposite chitosan/polyvinyl alcohol thin affinity membranes

Transport of copper ions through nanocomposite chitosan/polyvinyl alcohol thin adsorptive membranes has been mathematically investigated in the current study. Unsteady-state diffusive transport model was coupled with the Freundlich isotherm to predict the concentration of the ions in dialysis permeation operation. Pristine model was not successful in predicting the experimental data based upon its low coefficients of determination（0.1

A gene encoding AtPIP5K2 may be involved in regulating the sensitivity to osmotic stress

One mutant line eto with salt tolerance was screened from a T-DNA insertion mutant collection of Arabidopsis thaliana. In addition to a reduced rate of seed germination, NaCl and ABA also inhibited the growth and the greening of cotyledons of wild-type seedlings, but not the eto mutant. TAIL-PCR analysis showed that T-DNA tag insertion in the eto was located at nucleotide 27,502 in BAC F3M18, upstream （at position -487 relative to the translation initiation codon） of gene At lg77740 （encoding a putative phosphatidylinositol-4-phosphate 5-kinase, AtPIP5K2）. This inserted mutation cosegregated closely with the eto phenotype, Another analysis not only indicated that AtPIP5K2 transcript is expressed predominantly in roots and rosette leaves, but also showed the T-DNA insertion resulted higher accumulation of the AtPIP5K2 in eto mutant plants and did not influenced the expression of the upstream At lg77730 gene. This change may play an essential role in the tolerance of eto mutant plant to the osmotic stress.

A Mass Transfer Model Based on Individual Bubbles and an Unsteady State Film Mechanism

A gas-liquid mass transfer model based on an unsteady state film mechanism applied to a single bubble is presented. The mathematical model was solved using Laplace transform to obtain an analytical solution of concentration profile in terms of the radial position r and time t. The dynamic mass transfer flux was deduced and the influence of the bubble size was also determined. A mathematical method for deducing the average mass transfer flux directly from the Laplace transformed concentration is presented. Its accuracy is verified by comparing the numerical results with those from the indirect method. The influences of the model parameters, namely, the bubble size R, liquid film thickness δ, and the surface renewal constant s on the average mass transfer flux were investigated. The proposed model is useful for a better understanding of the mass transfer mechanism and an optimum design of gas-liquid contact equipment.

Direct Osmosis

Method of direct osmosis （also known as nonequivalent ion transfer through semipermeable membrane） was developed in 1971 and patented in 1974 by one of authors. There were no publications because the patent was secreted. Moreover, necessary quality of membranes--high negative selectivity and apparatus for this process was provided only in 2000s （patented in 2008）. Technology of direct osmosis is able to solve a number of problems of industry, such as extracting of rare elements （Re, Ge, U, etc.） from natural and manufacturing water. The authors need to mention that direct osmosis makes possible to create rentable technology of greenhouse gases trapping and burying. It will be shown in the next article. And this article is about the basic idea--nonequivalent ion transfer through semipermeable membrane or direct osmosis.

Shift in the percolation threshold of compressed composites—A 3D Monte Carlo simulation

The shift in the percolation threshold of compressed composites was studied by a 3D continuum percolation model. A Monte Carlo (MC) method was employed in the simulations. The percolation threshold was found to rise with the compression strain, which captures the basic trend in compression-induced conductivity variation from the experiments. Both fiber bending and texture formation contribute to the percolation threshold. The results suggest that fillers with a high aspect ratio are more desirable for sensor and electrical switch applications.

Penetration depth at various Raman excitation wavelengths and stress model for Raman spectrum in biaxially-strained Si

The carrier mobility of Si material can be enhanced under strain,and the stress magnitude can be measured by the Raman spectrum.In this paper,we aim to study the penetration depths into biaxially-strained Si materials at various Raman excitation wavelengths and the stress model corresponding to Raman spectrum in biaxially-strained Si.The experimental results show that it is best to use 325 nm excitation to measure the material stress in the top strained Si layer,and that one must pay attention to the distortion of the buffer layers on measuring results while 514 nm excitation is also measurable.Moreover,we established the stress model for Raman spectrum of biaxially-strained Si based on the Secular equation.One can obtain the stress magnitude in biaxially-strained Si by the model,as long as the results of the Raman spectrum are given.Our quantitative results can provide valuable references for stress analysis on strained materials.

INFLUENCE OF SLIP VELOCITY ON BLOOD FLOW THROUGH AN ARTERY WITH PERMEABLE WALL： A THEORETICAL STUDY

A theoretical investigation concerning the influence of slip velocity on the flow of blood through an artery having its wall permeable has been carried out. Here blood is treated as a homogeneous Newtonian fluid. The flow is characterized by three parameters： /3 the ratio of radius to length of the arterial segment, Re the characteristic Reynolds number associated with the pressure outside the arterial segment and c the filtration coe^cient. The problem has been solved by the use of a perturbation technique, e is considered to be very small, ensuring the validity of the perturbation method. The computed numerical results are presented graphically to depict the variations in velocity, volumetric flow rate, wall shear stress and flow resistance.