Wax DEPOSITION is one of major challenges in petroleum production and transportation. The formation of wax DEPOSITION reduces the effective pipe radius and decreases flow capacity of the pipe. Highly waxy crude oils can cause a blockage of a pipeline because of wax DEPOSITION during production and transportation of the crude oil. Wax DEPOSITION costs can be significantly reduced if wax DEPOSITION can accurately be predicted. The target of wax DEPOSITION modeling is to predict wax content and the thickness of DEPOSITION with location and time. For wax DEPOSITION modeling, it is required to study this phenomenon in laboratory flow loop experiments to investigate effective operation conditions such as flow rate on wax DEPOSITION. For wax DEPOSITION modeling, heat and mass transfer coefficients should also be calculated. Studies show that in laminar flow conditions, mass transfer coefficient can easily be calculated from Chilton-Colburn analogy. The use of analogy in turbulent flow conditions for calculating mass transfer coefficient overestimates the amount of wax DEPOSITION. In this work, a computational wax DEPOSITION model combined with the wax precipitation KINETICS in the boundary layer was developed. If wax precipitation KINETICS can accurately be predicted, it can significantly reduce mass transfer coefficient in turbulent flow conditions. Herein, a wax precipitation coefficient model for the prediction of mass transfer coefficient is suggested and shows that when wax precipitation coefficient increases, mass transfer coefficient decreases.

Having sufficient and accurate understanding about KINETICS of phenomena could be an important reason for further technological progresses. Finding a white-box mathematical model for weight vs. time curves of Electrophoretic DEPOSITION (EPD) using large and small signal analysis has been thoroughly studied in the present investigation. Weight-Time curves of nano-Mullite suspension have been trained using the Simulink modeling tool. Results of the investigation illustrate that, the frequency of particles, i.e., the probability of particles collision with each other decreases due to the reduction of the particles concentration in the suspension. When the solid load becomes higher close to the electrode surface, the mobility of an individual particle will be restricted and a collective pressure onto the particles closer to the electrode surface is supposed to develop. The accumulated particles will be forced to flocculate and form a solid packing structure. According to the results of modeling, the times before flocculation are suitable for DEPOSITION of a highly dense coating.

The aim of this study was to analyze the effect of drought stress on the KINETICS of leaf elongation in relationship to the variation of sugar concentrations and their net DEPOSITION rates along the elongation zone of leaf 4 of durum wheat plants. Plants were grown in soil in a naturally illuminated greenhouse, and water was withheld from seedlings for a period of 14 days. Leaf 4 of 26 day-old plants was used for growth measurements and tissue sampling. Relative elemental growth rates (REGR), cell displacement velocity (DV), and elongation zone length (EZL) were significantly reduced by drought treatment. Together, this resulted in a decrease in leaf elongation rate (LER) in drought-stressed plants. Epidermal cell length along the elongation zone was not significantly affected by drought stress, indicating that the decrease in elongation zone length was due mainly to a reduction in cell production rate. The concentration of total soluble sugars (TSS) and non-reducing sugars (NRS) was highest at the leaf base and decreased distally from 10 mm from the leaf base in plants grown under non-stressed (control) conditions. Drought stress caused a significant accumulation of TSS at the leaf base, mainly through an increase in non-reducing sugars. The continuity equation was used to calculate sugar net DEPOSITION rates. Drought stress increased the net DEPOSITION rates of non-reducing sugars in the first 10 mm from the leaf base. This increase was the principal source for the increase in non-reducing sugars concentrations at the leaf base in response to drought.

The Random DEPOSITION model is the simplest model for surface growth, where there is no correlation between the neighbor sites of the lattice. In the Ballistic DEPOSITION model, the particles stick to the first neighbor particle; thus it is used to describe the DEPOSITION of the sticky particles. However, in many true-life phenomena involving surface growth, there is no adhesion. Instead, the friction between the particles leads to interlocking particles and the formation of porosity inside the growing bulk. Presenting a discrete 1+1 dimensional model, we study this case. In this model, if a particle is trapped between two other particles from right and left, it will stay in that position, as an equivalent for friction. The growth and roughness exponents are calculated, close to the Ballistic model, although there is no lateral growth.

in this paper, KINETICS of DC electrophoretic DEPOSITION (EPD) of carbon nanotubes (CNTs) are investigated. Suspension of carbon nanotubes in pure ethanol with addition of magnesium nitrate was used as DEPOSITION media. The effect of main EPD parameters such as DEPOSITION time, applied voltage and the CNTs concentration on deposit yield were investigated. The variation of current density vs. time and the effect of magnetic stirring were also examined. The results are in good agreement with Hamaker’s law and the deposit yield increases with increasing of applied voltage and CNTs concentration but there is a deviation from linear trend in longer DEPOSITION times. Stirring could compensate some of this deviation but increases the current density fluctuations.

The purpose of this study was to investigate the DEPOSITION of the hydroxyapatite (HA) coating via the electrophoresis procedure. The HA DEPOSITION was performed in an ethanol, methanol, acetone and isopropanol suspension. Methanol was found to be the best DEPOSITION media. Among the different environmental conditions, including the encapsulation of the samples under two vacuum types of pressure (10-5-10-4 and 2x10-2 Torr) and also the purge of the argon gas in the tube-like furnace, the optimum environment was the one demonstrating the encapsulation under the vacuum pressure of 2x10-2 Torr (washing with argon gas of 99.9% purity). After the examination of 3 sintering temperatures (1020, 1050 and 1100oC), the sintering temperature at 1050oC illustrated the most desired results. The samples sintered under these conditions were apparently intact, most of the interfacial part of the coating was found to be attached to the substrate surface irregularities and no single cracks were observed.

Much importance was given to dry DEPOSITION over the past few decades as it deteriorated the environmental conditions and resulted in subsequent health effects. This paper starts with an overall scenario of dry DEPOSITION research; it focuses on: various particulate dry DEPOSITION flux measurement methods, comparison of various published numerical values on dry DEPOSITION velocity and factors controlling dry DEPOSITION velocity. This work provides a technical overview to research studies on the current state of dry DEPOSITION and limitations of various measurement methods. Relationship between dry DEPOSITION flux and particle concentration is discussed with the help of previous works. Various mathematical models used to predict dry DEPOSITION velocity are discussed. Dry DEPOSITION velocity of particulates around the world is compared to gain perspective on factors influencing dry DEPOSITION.