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As a key factor, it is vital to mathematically model the electrical efficiency of photovoltaic (PV) systems. This paper investigates the efficient modeling of a 2.5 kW grid-connected PV system, located in Mahan, Kerman, Iran, with respect to different factors like solar radiation, humidity, dust deposition, temperature, and shading. For this aim, different nonlinear models are considered and a curvefitting approach is used to optimally determine the unknown parameters. Over the case study, simulation results show that when the dust deposition is not included in the modeling (solar radiation, ambient temperature, cell temperature, humidity, and shading as inputs), the third-degree polynomial model leads to more accurate result than the other models. By use of the third-degree polynomial model, the value of root mean square error (RMSE) for train and test data sets is obtained 0.0123 and 0.0109, respectively. In this case, the average RMSE value is 0.0116. On the other hand, when dust impact is included in the modeling (solar radiation, ambient temperature, humidity, and number of dusty days as inputs), the accuracy of the exponential model is more than the other ones. In this case, the value of RMSE for both train and test data sets is obtained 0.0018. Sensitivity analysis shows that the system efficiency depends mainly on the radiation, cell temperature, and dust and less on the humidity. [ABSTRACT FROM AUTHOR]

Evaluation of wave impacts on submarine landslides is an essential element in geohazard studies. The slight desaturation of sediments (due to dissociation of gas hydrates) has been found to adversely impact the slide of the sloping seabed in the Fraser River Delta in Canada. In this study, to investigate the role of wave action on the slide of partially saturated seabed slopes, an integrated FEM model is developed. Despite most earlier studies that used a simplified decoupled undrained analysis, in this article, a more realistic model for coupled flow-and-deformation processes (within the sediments) and fluid-seabed interaction is utilized. Linear wave theory and Biot's poroelasticity for the fluid and seabed domains are considered, respectively, and continuity of flux and traction is enforced along the interface of the media. The instability of the sloping seabed is investigated using strength reduction finite element method (SRFEM) with Mohr-Coulomb failure criterion. The limitation of limit equilibrium methods in the evaluation of submarine landslides is shown through comparison with SRFEM analyses where partly-dynamic and quasi-static idealizations of seabed response are considered. Finally, the adverse impacts of slight desaturation on seabed instability are assessed, and the reduction of the stability number with seabed steepness is presented. [ABSTRACT FROM AUTHOR]

In this paper, the new concept i -isodominism between two graphs is introduced, where i is a positive integer. The i -isodominism is a pair of the graph isomorphism which depends on the smallest i -dominating sets. By this tool, a graph with one vertex, complete graphs, wheels and stars are in the same 1 -isodominism class. Furthermore, some results about the 1 -isodominism classes of paths, cycles and star polygon are presented. [ABSTRACT FROM AUTHOR]

The effect of mechanical activation on the synthesis temperature decreasing of silicon carbide was investigated and a kinetic model of a carbothermic reduction of silicon carbide was obtained. Silicon carbide was synthesized using silica activated in a planetary mill at different times up to 40 h under an argon atmosphere. Structural changes due to the milling and the reduction of the activated silica were studied by the X-Ray diffraction (XRD) method and non-isothermal TGA with a heating rate of 10 °C min-1 respectively. The kinetic model obtained by the fitting technique for an unmilled sample was found to be chemically controlled of the second order with E = 138.92 Kcal.mol-1 and A = 3.92×1015 s-1. For the sample milled up to 20 h, according to the Avrami-Erofeev3 equation; A = 1465633 s-1 and E = 66.71 Kcal.mol-1. [ABSTRACT FROM AUTHOR]