Mesh gradation control

This paper gives a procedure to control the size variation in a mesh adaption scheme where the size specification (the so-called control space) is used to govern the mesh generation stage. The method consists in replacing the initial control space by a reduced one by means of size or metric. It allows to improve, a priori, the quality of the adapted mesh and to speed up the adaption procedure. Several numerical examples show the efficiency of the reduction scheme. © 1998 John Wiley & Sons, Ltd.     

Deep graph transformation for attributed,directed, and signed networks

Knowledge and Information Systems - Generalized from image and language translation, the goal of graph translation or transformation is to generate a graph of the target domain on the condition of...     

Estimation of wax deposition in the oil production units using RBF-ANN strategy

Accurate prediction of the solid deposition is petroleum industry can result in increasing the production efficiency. This can also result in the elimination of a major industrial problem, namely the wax deposition. In this study, application of intelligent methods in prediction of the wax deposition is investigated by developing a radial basis function artificial neural network. Levenberg Marquardt algorithm is also applied to determine the optimum predictions. Results from the proposed model are also compared to Kamari et al. model revealing the better performance of the proposed RBF-ANN. The validity of the proposed model is also investigated using statistical and graphical approaches, illustrating the great capability of the proposed RBF-ANN in accurate prediction of the wax deposition. R-squared and mean squared error values of 0.9975 and 0.029251 are obtained for the proposed model, revealing the validity of the RBF-ANN in estimating the wax deposition.     

Application of ANFIS-GA as a novel and accurate tool for estimation of interfacial tension of carbon dioxide and hydrocarbon

In the recent years, the enhancement oil recovery processes become the one of the interesting topics in petroleum engineering because of declination of oil reservoirs. One of the most popular processes is the carbon dioxide injection that has special importance because of its environmentally friendly and high efficiency of displacement. The interfacial tension (IFT) between carbon dioxide and hydrocarbon is known as a key parameter in this process so in the present investigation the Adaptive neuro-fuzzy inference system (ANFIS) was coupled with Genetic Algorithm (GA) to create a novel tool for prediction IFT between carbon dioxide and hydrocarbon in terms of temperature, pressure, molecular weight of alkane, gas and liquid densities. The outputs of predicting model were compared with experimental IFT statistically and graphically. The comparisons showed that predicting model has acceptable accuracy in prediction of IFT of hydrocarbon and carbon dioxide.     

Narrowband optical filters suitable for various applications in optical communications

We propose three types of narrowband optical filters based on a Fox-Smith resonator. We demonstrate that by choosing the appropriate combination of coating materials on each prism facet, one can design either a high reflectance or a high transmittance optical filter, suitable for low bit rate optical communication applications with International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) standards. We also show the possibility of designing an optical filter having a desirable finite reflectance/transmittance ratio with simultaneous peaks at ITU-T standard wavelengths. Such filters could be suitable for wavelength tuning applications.     

Periodic graphene nanobuds: A novel Li-storage material

The characteristics of lithium adsorption on graphene and periodic graphene nanobuds (PGNBs) have been studied by means of density functional theory calculations. All calculations have been performed within the Perdew–Burke–Erzenhof functional as implemented in the SIESTA package, with a double-ζ plus polarization basis set. Several starting configurations were considered for interacting systems. The results show that the Li atom is strongly adsorbed on a pure graphene with a binding energy of about −0.85 eV. However, the binding energy enhances to −2.58 eV when Li binds to a PGNB at the hollow site above the center of the nonagon ring. It was found that the increase in binding is due to significant charge transfer from the Li to the PGNB. The stability of the Li/PGNB system was evaluated within ab initio molecular dynamics simulation which has been carried out at room temperature. The very favorable binding energy obtained as well as high specific surface of PGNB (due to attached fullerenes) suggest a considerable possibility to experimentally apprehend these novel systems as a superior media for Li ions storage.     

Flow of Microencapsulated Phase Change Material Slurry through Planar Spiral Coil

Forced convection cooling is an effective method in thermal management that relies mainly on dissipating heat by pumping heat transfer fluid (HTF) through the heat source. In this paper, we investigate the thermal properties enhancement of dielectric water as the HTF. To enhance the properties of the HTF, microencapsulated phase change materials (MPCM) will be added to the base fluid. The MPCMs are composed of phase change material (PCM) encapsulated with shell materials. The PCM inside the capsules may undergo a phase change. This leads to a significant heat gain and release. The numerical model is developed to solve for continuity, momentum, and heat transfer equations using the finite volume method. The behavior of the MPCM slurry in curved channels, generates unique patterns due to different viscosity values and the centrifugal forces. Our preliminary numerical data on MPCM slurry through planar spiral coil heat exchangers show the new patterns of velocity and heat transfer curves. The current paper studies the steady condition of laminar flow at different boundary conditions. The velocity and temperature profiles, heat transfer data with different mass fractions of MPCM additives to the base fluid, and their heat removal capabilities are quantified and discussed in detail.     

Effect of Nanocrystallization on Discharge Behavior and Microstructure of Plasma Electrolytic Oxidation on AZ31B Alloy

In this study AZ31B Magnesium alloy was pre-treated with surface mechanical attrition process (SMAT), for nanocrystallization, and subsequently plasma electrolytic oxidation was applied. Real-time imaging and microscopic investigation were used to study discharge events to reveal the pre-treatment effect on coating growth. SMAT processing developed a 100 nm nano-crystalline layer. Nano-crystallinity was verified by XRD and TEM studies which showed that treated area has crystalline size of about 30 nm. SEM studies revealed that in first minute number of discharges on nano-crystalline surface was 50% higher than microcrystalline surfaces. Number of discharge channels in both samples became nearly identical in longer treatment times. Most of the changes in growth rate are focused in first 2 minutes of coating. Calculations revealed that for pre-treated sample extracted volume of molten oxide through each discharges is significantly higher than non-treated sample while the number of discharges are less. However, number of discharges decline rapidly. While oxide layer grows the surface reactivity decreases.