Sharif Digital Repository

The aim of the present work is to propose an eco-design method for sustainable development of methanol production by implementing a multi-objective optimization model based on CO2-efficiency. Two different approaches for the methanol production, i.e. a conventional reference methanol case (RMC) and proposed green integrated methanol case (GIMC) were compared from the view point of eco-design. Using life cycle assessment and process simulation, the environmental features as well as operational decision variables of the RMC and GIMC were assessed. Based on the inventory analysis of LCA, it was found that carbon dioxide is the major emitted pollutant from methanol production. Thus the... 

The use of parallel converters is one of the most practical solutions to solve the problem of transmitting bulk power generated in megawatt wind turbines to the grid. In spite of several advantages of paralleling, some considerations must be taken into account. Zero-sequence circulating current flowing between parallel converters is one of these concerns. Characteristic differences and discrepancy of zero-axis duty cycles of the parallel converters are considered as the main origins of this current. This paper investigates another source of this phenomenon in space vector modulation controlled converters. This unnoticed source is the notable third-harmonic voltage generated in the... 

Migration from Two Dimensional Integrated Circuits (2D ICs) to Three Dimensional Integrated Circuits (3D ICs) reduces the delay due to the shorter wire length between sender and receiver. However, Through-Silicon-Vias (TSVs) that connect layers in the structure of 3D ICs can seriously increase the delay due to capacitance coupling between TSVs and lead to crosstalk fault. The severity of crosstalk faults depends on transitions appearing on TSVs that is called transition patterns. To propose an efficient crosstalk tackling mechanisms in 3D ICs, an accurate probability analytical model is required to predict the delay caused by TSVs (3D ICs) in the attendance of these transition patterns. In... 

Greenhouse gas emissions from anthropogenic sources are believed to be the main cause of global warming and climate change. Furthermore, fossil fuels are forecasted to remain the dominant source of energy in the near future. Therefore, capture and sequestration of greenhouse gases and in particular carbon dioxide is likely to be a major pathway toward environmental protection and energy sustainability. Such clarity has stimulated an intense and diverse range of research into various capture and mitigation technologies, which race with global warming in real-time. Quantification of the performance improvement rates of these technologies can inform decision-makers' long-term investment... 

Extensive dependence of the national economy on wasteful fossil fuel use as well as limited access to the international financial markets and the best available techniques over the strict economic sanctions period have hindered Iran from developing a sustainable energy system. By considering the reversal order, the present study investigated the least-cost options for improving energy efficiency and reducing GHG emissions in the energy supply sector. The essential purpose of this research work is to increase the evidence base necessary to inform policy and strategy discussions within Iran and related communities concerning the choice of GHG emissions reduction. Applying ARDL approach to... 

In upstream oil industry, microorganisms arise some opportunities and challenges. They can increase oil recovery through microbial enhanced oil recovery (MEOR) mechanisms, or they can increase production costs and risks through reservoir souring process due to H2S gas production. MEOR is mostly known by bioproducts such as biosurfactant or processes such as bioclogging or biodegradation. On the other hand, when it comes to treatment of reservoir souring, the only objective is to inhibit reservoir souring. These perceptions are mainly because decision makers are not aware of the effect microorganisms’ cell can individually have on the wettability. In this work, we study the individual effect... 

Despite that the border between chaotic and stochastic systems is exactly defined, scientists, use high dimensional chaotic dynamics to model numerous stochastic models and sometimes use stochastic models to study chaotic systems. In this paper, we have investigated chaotic systems with a stochastic approach and proposed an estimator for the chaotic system which is used to present different algorithms for chaos control, extreme event prediction and extreme event mitigation. The stochastic estimator is constructed by meshing the phase space and applying the cell mapping method (with some considerations) which provides us with a model-free approximation of the systems. The algorithms are ideal... 

In the study, the daily and monthly performance of a photovoltaic thermal system integrated with phase change material is investigated in Shanghai, China. A three-dimensional model of photovoltaic thermal system integrated with phase change material system is developed and numerically simulated. Water is considered as working fluid, and the fluid flow regime is laminar and incompressible. Both quasi-steady and transient models are compared together, and the transient model is selected because of its higher accuracy. Validation analysis is performed on the numerical model to show the reasonable agreement of current research compared to some other research. After obtaining the suitable... 

Controlling evaporation plays an essential role in arid and semi-arid water resources systems where it accounts for a considerable amount of reservoirs outflow. In this study, we have evaluated evaporation reduction efficiency of different kinds of self-assembled nano-thickness films. The films consist of six different combinations of stearyl and cetyl alcohols with additives such as jojoba oil, stearic acid, and calcium hydroxide. The study lasted from July to August and utilized two pairs of class A evaporation pans: one pair was semi-floating on Chitgar lake water surface while the other one was located on the shore. The experimental results showed that a monolayer containing 3:1 stearyl... 

Radon is released from soil and building materials and can accumulate in residential buildings. Breathing radon and radon progeny for extended periods hazardous to health and can lead to lung cancer. Indoor air conditions and ventilation systems strongly influence indoor radon concentrations. This paper focuses on effects of air change rate, indoor temperature and relative humidity on indoor radon concentrations in a one family detached house in Stockholm, Sweden.In this study a heat recovery ventilation system unit was used to control the ventilation rate and a continuous radon monitor (CRM) was used to measure radon levels. FLUENT, a computational fluid dynamics (CFD) software package was...