Sharif Digital Repository

Marine risers are tubular components, which are used to transfer fluids between seabed and floating platform. They may have a great share in cost of oil and gas production systems. One of the risers used in deep-water, is Steel Catenary Riser which is an economic alternative. However, amongst issues in designing this type of risers, high stress level in floating platform connection point and seabed touch- down zone is notable which is created due to platform movements, currents and wave loading and finally, leads to fatigue life reduction. Using buoyancy modules which are attached to risers is one of stress levels reduction solutions in hotspot points. In this study, considering the Caspian... 

The derivatives of 5-Hydroxy-3(2H)-pyridazinone show inhibitory effects on hepatitis C virus. The aim of the present work was modeling and prediction of inhibitory effects of these derivatives (Log(1/EC50)) on this disease. In this research, a data set of 119 molecules of 5-Hydroxy-3(2H)-pyridazinone derivatives that have inhibitory effect on hepatitis C virus was selected. The MLR model was generated using SPSS package. Five important descriptors were selected applying stepwise variable selection technique. These descriptors selected through 1207 descriptors that were calculated for all molecules in data set. Best model with high R2 and F values and low RMSE was selected for the... 

Prevalence of Multiple Drug Resistant Tuberculosis and use of Yersinia-Pestis in bioterrorism warrants synthesis of new antimicrobial agents. Although Pyrazoline derivatives were first synthesized as antimicrobial drugs, but they also had Mono Amine Oxidase inhibitory effects. In this Quantitative Structure – Activity Relationship (QSAR) study, MAO-I activity of pyrazoline derivatives were evaluated. By applying semi-empirical quantum calculations at AM1 level, optimum 3D geometry of 32 molecules were obtained.After descriptor generation, Principal Component Analysis (PCA) was performed to fiind out 5 outliers. After omitting outliers and sorting molecules according to IC50 values, Stepwise... 

Since early civilizations underground water pipes have played a major role on promoting human being life style. Today, centuries after designing water mains equipment, utilizing a water distribution and sewage collection system is matter of great necessity in modern metropolises. In current research the pilot area is located in the city center .the major motivation for opting such area was extraordinary breakage rate which was unseen on other city areas and nearby cities. Data pertaining to four commonly used pipe material were collected. Preliminary data quality analysis was conducted to detect distinct contradictions. On basis of collected data, breakage rate plots were depicted for each... 

Epidemiological studies have shown a positive association between particulate matters exposure and adverse health effects. However, the insufficient knowledge about the influences of components or characteristics of these particles on their health effects and toxicity leads into inefficient control practices for reducing particulates health effects. So, relationship between particles toxicity and their emission sources and components is a valuable criterion in particle emission control strategies. Moreover, as people spend most of their time in indoor environment, investigating the main sources and components of particulate toxicity in indoor environment and finding the influence of outdoor... 

Today, the importance of scientific collaborations is due to the fact that researchers who jointly publish an article, research connections are formed between them, and as a result, professional learning is obtained. Each of these researchers brings a feature and advantage to the research team, such as mastering a particular topic and its subdivisions, team thinking, and division of labor between them. The importance of these collaborations is doubled when researchers collaborate with each other at the international level, because the networking of researchers through collaboration with colleagues from different countries, especially central and developed countries in science, in addition to... 

Vehicle Kilometers of Travel (VKT) as one of the most important indicators of travel behavior, express the total kilometers traveled by all vehicles on city networks. Due to the expansion of urbanization and, consequently, the growth of cities, the need for awareness of citizen’s travel behavior and planning for it, is felt in more cities. Spatial transfer of a model which refers to transfer a model from on region (context) to another one, helps different regions to benefit from the results of modeling with a relatively low expense.The main purpose of the research was evaluating spatial transferability of models developed to estimate VKT in three metropolitan cities of Iran which are... 

Demand estimation has always been one of the most important components of marketing in all industries. Because the profitability of any organization depends on the demand for the product or service that the organization offers to the market. On the other hand, in order to optimize the performance of the organization and better planning, we need to have an estimate of demand in order to avoid wasting the available facilities by optimally allocating resources. Another issue that shows the importance of demand estimation is the dependence of optimal pricing on the amount of demand, which can be said to be the most important tool of the organization to manage its revenue. Optimal pricing can be...