Sharif Digital Repository

The present study investigated the effect of laser input energy on the quality and mechanical behavior of a 304 stainless steel–polyamide 6 joint in the laser-assisted metal and polymer direct joining (LAMP) method experimentally and numerically. After the proposed heat transfer model was validated, it was determined whether there was an optimal amount of laser input energy that could produce a joint with favorable quality and mechanical behavior. Among different laser input energies used in this study, 28-J/mm energy can provide more uniform and extensive wetting of the metal surface by the polymer, while excessive polymer degradation in the joint zone was prevented. As a result, an optimal... 

The paper presents a comprehensive electric arc furnace (EAF) model, developed for simulation and model-based control of the EAF processes. The model consists of three sub models, i.e., (i) arc model; (ii) chemical and slag model; and (iii) heat-transfer model. Arc model predicts the amount of energy dissipated from the arcs using arc currents and arc lengths; chemical and slag model calculates chemical energy and changes of elements/compounds, slag height and slag quality; while the heat-transfer model uses calculations of the other two models in order to establish a reference energy system (RES) for each zone in the EAF due to the variations in arc length, slag height, and bath height. The... 

The use of solar concentrators can be an alternative for initial cost reduction in the PV systems. However, they suffer from high cell temperature that can be overcome by different active or passive cooling approaches. Spectral splitting and the elimination of high-energy solar photons are effective solutions for cell temperature reduction. In this study, we developed a Polymethyl methacrylate Spectral Splitting Fresnel Lens (SSFL) for linear concentration using a new design, which directs the desired portion of the spectrum towards the cell and diffracts the rest to eliminate the use of beam splitters or nanofluids in the spectral splitting system. Different SSFLs were considered for... 

The proper modeling of radiation is of great importance in numerical simulation of combustion processes. A simple gray weighted-sum-of-gray-gases (WSGG) model has been intensively used in CFD simulations of industrial combustion applications, mainly because of its low computational costs. However, the gray assumption is far from the real behavior of non-gray combustion gases. This could consequently affect the accuracy of temperature field and heat flux distribution predictions. On the other hand, modern non-gray global radiation models such as the standard spectral line-based weighted-sum-od-gray-gases (SLW) model are still computationally expensive for many engineering purposes. To... 

Greenhouses require energy in order to provide a proper environment for crop production. Utilizing solar energy in solar greenhouses is a sustainable solution to face this problem. In this study, a solar greenhouse concept is considered, and a dynamic thermal model is developed to predict the inside air temperature. The model is integrated into an optimization procedure to find the optimal greenhouse design that has the best thermal performance by adjusting its structural parameters. This optimization procedure provides a tool to find the optimal solar greenhouse design for each climate condition and predict its performance. For instance, for the case study of Tehran (Iran), the optimal...