Effects of leachate infiltration and desiccation cracks on hydraulic conductivity of compacted clay

Both cracks in clay liner and the complex composition of landfill leachate might have effects on the hydraulic conductivity of a compacted clay liner. In this study, the hydraulic conductivities of natural clay and bentonite-modified clay with and without desiccation cracks were measured, respectively, using three types of liquids as permeating liquid： 2 500 mg/L acetic acid solution, 0.5 mol/L CaCl2 solution, and tap water. When tap water was adopted as the permeating liquid, desiccation cracks resulted in increases in the average value of hydraulic conductivity： a 25-fold increase for the natural clay and a 5.7-fold increase for the bentonite-modified clay. It was also found out that the strong selfhealing capability of bentonite helped to reduce the adverse impact of cracks on hydraulic performance. In contrast to tap water, simulated leachates（acetic acid and CaCl2 solutions） show no adverse effect on the hydraulic conductivities of natural and bentonite-modified clays. It is concluded that desiccation cracks and bentonite have more significant effects on hydraulic performance than simulated leachates.

Numerical Simulation for Bioconvection of Unsteady Stagnation Point Flow of Oldroyd-B Nanofluid with Activation Energy and Temperature-Based Thermal Conductivity Past a Stretching Disk

A mathematical modeling is explored to scrutinize the unsteady stagnation point flow of Oldroyd-B nanofluid under the thermal conductivity and solutal diffusivity with bioconvection mechanism.Impacts of Joule heating and Arrhenius activation energy including convective boundary conditions are studied,and the specified surface temperature and constant temperature of wall(CTW)are discussed.The consequences of thermal conductivity and diffusivity are also taken into account.The flow is generated through stretchable disk geometry,and the behavior of non-linear thermal radiation is incorporated in energy equation.The partial differential equations governing the fluid flow in the structure is reduced into dimensionless nonlinear ODEs by applying suitable similarity variables.The obtained system of non-dimensional nonlinear ODEs is treated numerically with the help of bvp4c solver in Matlab under shooting algorithm.The impact of various prominent parameters on velocity profile,thermal profile,volumetric nanoparticle concentration and microorganism distribution is depicted in graphical form.The numerical outcomes for skin friction coefficient,heat transfer rate,Sherwood number as well as microorganism density number versus various parameters are listed in the tables.The results show that fluid velocity is reduced by increasing buoyancy ratio parameter,while the fluid flow increases with mixed convective parameter.The temperature profile is enhanced with the amount of nonlinear thermal radiation and temperature dependent thermal conductivity.Furthermore,concentration profiles of nanoparticles have opposite behavior for Brownian motion coefficient and thermophoresis diffusion parameter,and it is noticed that by varying Peclet number the microorganisms profile is declined.The proposed study is useful to control and optimize heat transfer in industrial applications.

Solutions of the modification heating conduction equations of a kind of laser thermal effect

This paper has solved the Chester modified heat conduction equation of the different relaxation time r value under different temperature conditions, different boundary conditions and the different initial conditions by different means of methods. These solutions can help to obtain temperature field of laser thermal effects.

Structures of sodium vanadate solution under different conditions

Combined with Fourier transform infrared spectroscopy（FTIR） analysis of sodium vanadate solution,the relationship between conductivity and structure was investigated by measuring the electric conductivity of the solution under different alkali concentrations and molar ratios of NaOH to V2O5. Results suggest that the polymerization vanadium acid radical ions gradually transform into monomer with the solution diluting. When the solution is diluted to a certain extent,only the vanadium acid radical ion with V-OH chemical bond exists in the solution. At NaOH concentration of below 105.21 g·L^（-1）,the vanadate anions mainly exist in the form of vanadium acid radical ion with V-OH chemical bond and the ion transference number is approximately from 0.58 to 0.82. In the medium NaOH concentration range of 105.21-117.03 g·L^（-1）, the vanadate anions mostly exist in the form of vanadium acid radical ion with V-OH and V-O-V chemical bonds and the ion transference number is approximately 3.29. At NaOH concentration of above 117.03 g·L^（-1）, vanadate anions exist in the form of vanadium acid radical ion with V-OH and V-O-V chemical bonds.