The Effect of Cu (II) on Swelling and Shrinkage Characteristics of Sodium Bentonite in Landfills

Wastes in municipal landfills will release heavy metal cations over a long period of time. Therefore, the objective of this paper was to investigate the effect of copper (Cu) in the leachate from landfill on the swell-shrinking potential of bentonite liner. Copper sulfate solution with 4 different groups of concentrations (0 g/L, 2.5 g/L, 5 g/L, 10 g/L) were added to bentonite for conducting a series of swelling and shrinkage experiments. Then the Does Response model was used to describe the swelling and shrinkage process of bentonite in different copper sulfate solutions and the applicability of the model was evaluated. At the same time, clay mineral analysis experiments (XRD and XRF) were carried out to analyze the variation of interlayer space and element content of montmorillonite. The results show that the swell volume of bentonite decreases with the increase of the concentration of Cu (II). The rate of swelling was high and inversely proportional to the concentration of Cu (II). The shrinkage curve of bentonite could be divided into uniform velocity stage, variable velocity stage, and stable stage. The shrinkage rate at the uniform velocity stage and shrinkage at the stable stage decreased with the increase of the concentration of Cu (II). The model was suitable for describing swelling (or shrinkage) curves with smaller expansibility (or shrinkage). Results of XRD and XRF show that the erosion of Cu (II) led to the decrease of Na+ content in sodium bentonite, and then narrowed interlayer space of montmorillonite. When the solution concentration increases, both values of interlayer space of montmorillonite and Na+ content in sodium bentonite become lower, and that led to swelling and shrinkage of bentonite liner was getting smaller and smaller.

Atomism

Epicurus maintained that the universe is composed solely of microscopic material entities called “atoms” (Greek for “unsplittable”) and void; atoms have only the properties of shape, size, weight, and resistance, whereas void or space is extended and penetrable. All perceptible qualities, such as sound, color, and even thought, are the result of specific combinations of atoms, which are themselves composed of theoretically indivisible units called minima. Space and time are similarly quantized, and atoms travel at a uniform velocity of one minimum of space per minimum of time. There are infinite atoms in infinitely extended space, but only an incomprehensibly large but not strictly infinite variety of atoms; it is suggested that this quantity is a specific order of magnitude (like the modern “omega number”), and is the inverse of the minimum; in turn, all atoms are composed of an incomprehensibly large number of minima. This conception of point-like but extended minima escapes some of the objections posed to the theory, such as the incommensurability of side and diagonal in a square. The tendency of atoms to fall is a result of the fact that they emerge from collisions in a favored direction, which by definition is down (comparable to the absence of left-right parity in modern physics). The Epicurean swerve is a sideways motion of one minimum, and prevents the perpetual collisions of atoms from resulting in their uniform downward motion.

Flow of a viscous fluid over an infinite rotating and porous disk with stretching (shrinking) effects

A viscous flow is maintained over a porous and rotating disk. The porous disk is stretched (shrunk) with the non-uniform velocity in the radial direction. Note that the viscous fluid is injected (blown) normally with non-uniform velocity. The study is under taken by considering the combined and individual effects of injection (suction), stretching (shrinking) and rotation. The kinematics properties associated with the disk are depending upon the radial coordinate. The governing partial differential equations (PDE’s) are simplified and transformed into a new system of DE’s. The set of boundary value ODE’s is solved with the help of a numerical method. The transformed equations (presented over here) are new and to the best of authors knowledge, the equations are not published in literature. In particular cases, the modeled equations may reduce to the classical problems of rotating disk flows. The previous models of rotating disk flows with or without porosity and stretching (shrinking) effects are summarized into a single model. For fixed value of the governing parameters and different sizes of "infinity", no increase/decrease in the thickness of boundary layer is seen but the profiles of velocity components and pressure are significantly changed with the different levels of "infinity".

DEVELOPMENT AND RESEARCH OF VIBRATION IRREGULARITY IN PIPING SYSTEMS AND PATHS OF TURBOMACHINES ON THE BASIS OF MATHEMATICAL MODELING

The present paper presents a comparison of the performance of different flow conditioners. The numerical investigation is carried out using ANSYS FlUENT. Flow conditioners efficiency is evaluated on the basis of the ability of these devices to produce a uniform velocity profiles with low pressure loss under high-level disturbance conditions, such as those produced by gate and ball valves. A new flow conditioner device, which consists of two perforated conic plates has been designed, and demonstrated a high performance within a short distance downstream of the flow conditioner.