Sharif Digital Repository

The purpose of this study is to develop a new optimal solution method for controlling the greenhouse climate and minimizing energy demand for heating and cooling the greenhouse. As greenhouses move towards more advanced structures and technologies, the need for advanced control will be more important in order to reduce energy consumption. More comprehensive and accurate mathematical models are needed for complex systems, multiple inputs and multiple outputs to make system behavior perform better and more efficiently. In this research, a new method has been developed for optimal control of the greenhouse and a specific greenhouse climate model is used which is based on optimal closed loop... 

Nowadays, modern life needs energy resources. In the last few centuries, countries have focused on the use of fossil fuels. However, excessive use of fossil fuels, such as oil and coal, has resulted in enormous environmental hazards. Global warming and air pollution are the most visible manifestations of these hazards. In recent years, energy researchers have been looking for alternative sources. The result of this approach is to pay attention to clean and renewable resources such as wind energy.Wind turbines are used to generate electrical energy out of wind. Among the different types, floating offshore wind turbines have been mostly considered because of various benefits. However, they... 

In this thesis, the molecular dynamics simulation is used to investigate the melting transition of B-DNA molecule, via of configurational entropy, the fraction of broken hydrogen bonds (f-curve) and hydrogen bonding energy.We have performed molecular dynamics simulation on Drew-Dickerson oligomer with sequence of (CGCGAATTGCGC) at different temperatures, within the range of 280-400 K with the 20 K intervals. The simulation was done in two different mediums (pure water and 1 M NaCl), to see influences of water and salt in stabilizing the DNA molecule. At each temperature, configurational entropy is calculated by the Schlitter’s formula, using the Cartesian coordinate of all atoms. So, in each... 

In recent years, nanodiamond (ND) has been used as reinforcement in polymeric nanocomposites in order to improve mechanical properties, thermal conductivity, etc. The surface of nanodiamond has several functional groups which make it appropriate adsorbent. In this study, nanodiamond was modified with dodecylamine corrosion inhibitor and was utilized (1wt %) in epoxy based nanocomposite. Fourier transform infrared spectroscopy (FTIR) analysis was used to confirm the surface modification of Nanodiamond. In order to estimate the loading amount of corrosion inhibitor, thermogravimetric analysis was investigated. FE-SEM analysis demonstrated nanoparticle dispersibility in epoxy matrix. Regarding... 

One of the ways that corrosion control is presented is the use of coatings that have good properties such as high adhesion, impact resistance, ultraviolet radiation, and so on. They also have other unique properties like anti-corrosion property. To achieve coatings with these advanced properties, they use special properties of nanocomposites. Nanocomposites can add or improve one or more properties to coating properties.In the present study, we tried to first synthesize NanoDiamond/Polyaniline hybrid nanoparticles in different percentages and then use this hybrid in epoxy ester coating. To characterize this hybrid, various analyzes such as FE-SEM, TEM, FT-IR, UV-Visible, TGA and XRD were... 

Water Gas Shift (WGS) reaction is an old reaction in which syngas is used for producing Hydrogen. At the present time, the major application of this reaction is in fuel cells, since the necessary Hydrogen for these cells is provided by this reaction.
The present study investigate the influence of different preparation methods on properties of Cu-ZnO/Al2O3 catalyst for water gas shift (WGS) reaction, which is now known as the Commercial catalyst for low temperature WGS, and its influence on performance of Cu-ZnO/Al2O3 catalyst to derive an optimal Cu-ZnO/Al2O3 catalyst for water gas shift (WGS) reaction. Cu-ZnO/Al2O3 catalysts was synthesized by CP, DP, DP-Ultra, IWI , CP-Urea, and... 

Critical flux is an important parameter in membrane bioreactors, which studying it can give a better understanding of treatment by these bioreactors and make utilizing them easier. In this study, the effect of some sludge properties like it’s concentration, sludge volum index, concentration of protein and carbohydrate in EPS and SMP and the effect of some operating conditions like aeration flow rate and rest mode on critical flux in a submerged membrane bioreactor are investigated. In addition to comparison of TMP-t figures drived from flux step experiment, the hystersis figures are also compared. Finally, two long term experiments at two sub critical fluxes are done in order to study the... 

In this study, an efficient and cost-effective ternary Cu2O/r-GO/GQD photoelectrocatalysts was synthesized for the CO2 reduction reaction (CO2RR) using a simple and economical fabrication method. The primary objective was to overcome the inherent instability of Cu2O and enhance the selectivity toward multi-carbon products. The results demonstrate that the integration of reduced graphene oxide (r-GO) and graphene quantum dots (GQD) into the cuprous oxide structure narrows the energy bandgap from2.101eV to 1.921eV while significantly enhancing electrical conductivity. The optimized catalyst (1 wt% r-GO and 3.5% GQD) exhibited a current density of -8.035 mA/cm^2 at -1.6 V and -1.747 mA/cm^2 at... 

Dimethyl Ether (DME) is a pure and economic fuel which can be used as a suitable alternative for diesel fuels. Two processes are traditionally used for DME synthesis: producing methanol from synthesis gas and then dehydrating it to DME (direct process), and converting methanol into DME in a catalytic dehydration reactor over a solid-acid catalyst (indirect process), in which the indirect process seems to have economical advantage. In this research, the γ-Al2O3 catalyst was synthesized through precipitation process and then characterized by powder X-ray diffraction (XRD) and porosimetry analysis. Afterwards this catalyst was utilized in methanol dehydration reaction in a slurry reactor. Next,... 

The characteristics of the brine-crude oil interface in hydrocarbon reservoirs are very important, especially during water-based enhanced oil recovery (EOR) operations such as low-salinity waterflooding. At the interface of the two aforementioned fluids, the interaction mechanisms between the molecules of these two non-miscible fluids would affect capillary forces hence the efficiency of the EOR method. However, based on the published literature, there are still many open questions and uncertainties about the interaction of oil and brine molecules at the interface and their roles in the interfacial tension (IFT) changes for different oil and brine compositions. In this regard, molecular... 

The high consumption of worldwide fossil energy and its detrimental effects on the environment and climate have prompted a transition toward renewable energy sources. The availability of renewable energy sources depends on weather and seasonal changes; therefore, an imbalance between supply and demand would be unavoidable. Hydrogen storage as an energy carrier, can fulfill this energy mismatch. Storing hydrogen in underground formations, such as aquifers, has been the subject of extensive research recently. In these storage reservoirs, hydrogen contacts the resident brine which will be lost through the dissolution-diffusion mechanism. Therefore, successful design of these storages requires... 

Hydrogen is recognized as a clean energy carrier, playing a crucial role in energy transition. Subsurface formations, such as aquifers with large storage capacities, present economically viable options for hydrogen storage. However, optimizing the storage and recovery of hydrogen depends significantly on the wetting behavior of surfaces under various conditions. Determination of the wetting properties under different conditions is challenging due to experimental limitations, safety concerns, and the time required for tests, all of which can impact the efficiency of the process. For this reason, limited data are available in the published literature on the wettability of... 

Various studies have confirmed that water salinity and its composition significantly affect the efficiency of the waterflooding process. Field-scale operation of low-salinity water injection has been proven to be a cost-effective enhanced oil recovery (EOR) method which is also compatible with the environmental regulations. Although this method has satisfactory results, it faces some challenges, such as in-situ mixing of the injection low-salinity water with the saline water in the host reservoir. The salinity of the injected water increases, as it contacts the high-salinity reservoir brine in the pores. This phenomenon significantly impairs the efficiency of this technique, and increases...