Sharif Digital Repository

The Jajrood River watershed is on of the main drinking water resurces of Tehran, the capital city of Iran. In addition it provides many recreational usages. However, a variety of microbial pollutions is commonly perecived in the Jajrood River, among them a high concentration of coliform group bacteria that has caused strong concerns. In this article, different aspects of microbial pollution as well as the main microbial pollution sources in the region are discussed. Coliform group bacterial die-off rates have been evaluated as the key parameters that govern bacterial fate in the watershed and were estimated using both laboratory and field data investigations. The high values of the bacterial... 

The ultimate purpose of the nuclear power plant safety is to protect the public and the environment from unacceptable radiation exposure in all operational states. This paper presents a novel severe accident management framework to cope with the risk of radioactive material release to the environment. The objective is to reduce the contribution of severe accidents to the large and early release frequencies of radioactive materials for a VVER-1000 nuclear reactor. The proposed approach includes the emergency actions of NPP personnel aiming to recover the lost alternating power and restore the core cooling process by all means available at the site. In addition, mobile equipment including a... 

The steady 2-D boundary layer flow over a flat plate is studied analytically by homotopy perturbation method to analyze the entropy generation inside the boundary layer with constant wall temperature. By the transformations of go-verning equations including continuity, momentum, and energy by similarity va-riables, a dimensionless equation for entropy generation inside the boundary layer is obtained. The effects of important parameters such as Reynolds and Eck-ert numbers are investigated and the physical interpretations of the results are explained in details  

The production of porous (SAFFIL) preforms and SAFFIL/SiCP hybrid preforms will be discussed. SAFFIL fibers and SiCP are dispersed into an aqueous medium that consists of colloidal silica binder, distilled water, dispersants and deflocculants using agitation, spontaneous sedimentation, followed by drying and final strengthening. The effect of different process parameters such as various deflocculants and surfactants on the mechanical properties, mixing time and volumetric change of these preforms will also be investigated  

Background: Early prediction of symptoms and mortality risks for COVID-19 patients would improve healthcare outcomes, allow for the appropriate distribution of healthcare resources, reduce healthcare costs, aid in vaccine prioritization and self-isolation strategies, and thus reduce the prevalence of the disease. Such publicly accessible prediction models are lacking, however. Methods: Based on a comprehensive evaluation of existing machine learning (ML) methods, we created two models based solely on the age, gender, and medical histories of 23,749 hospital-confirmed COVID-19 patients from February to September 2020: a symptom prediction model (SPM) and a mortality prediction model (MPM)....