Sharif Digital Repository

The increasing rate of population and agricultural development over the past few decades has led to a significant rise in the pollution of surface and groundwater. The application of animal and synthetic fertilizers containing phosphorus, which increases the levels of this element in the soil, can be considered one of the factors endangering the environment, especially the quality of surface waters. The transport of phosphorus, which is one of the pollutants in agricultural runoff, can lead to the degradation of aquatic ecosystems and reduce the quality and usability of water resources. Accordingly, various numerical models have been developed to simulate phosphorus loss from the soil. They... 

The country's increasing demand for water makes effective dam management essential. Beyond environmental concerns, constructing new dams and their components involves relatively high costs. One of the most critical components of a dam is its spillway, which accounts for a significant portion of the total construction costs and plays a vital role in water resource management. To reduce spillway construction costs, a specific type of spillway that combines a stepped spillway with cascading basins can be employed. Designing this type of spillway can be considered as an optimization problem, requiring the use of optimization methods. Metaheuristic algorithms, which have gained significant... 

Enormous amounts of water and energy are lost by scrubber utilization for furnace exhaust gas washing during direct iron reduction process. Hence, the aim of the current research is design and construction of a system which could be employed instead of scrubber within direct iron reduction process considering the equipment size constraints.To this end, the substitute system was manufactured after dimensional analysis and simulation of lab model compared to the prototype regarding the implementation limitations. The model has been tested in different operating conditions and empirical relations have been extracted for general analysis of direct iron reduction process. The case study here is... 

The Revenue management concept has been studied and noticed by researchers for more than forty years. Although the applications of revenue management grow in different industries continuously, airline industry which is the origin of this research area is the pioneer of developing and representing new models. In the last few years, there has been a trend to enrich traditional revenue management models. In this thesis we first, reviewed most aspects of revenue management studies especially in airline industry, then choice-based customer behavior concept is introduced. Also a case sample study in customer choice behavior has been developed with time scale considering and remodeled. According to... 

At the early stages of production, oil reservoirs may have enough energy to push the oil from the reservoir into the wellbore and subsequently from the wellbore to the surface. When the reservoir energy is too low for the well to flow, or the production rate desired is greater than the reservoir energy can deliver, using some kind of artificial lift method to provide the energy to bring the fluid to the surface, seems to be necessary. Continuous flow gas lift is one of the most common artificial lift methods widely used in the oil industry during which, at appropriate pressure, gas is injected in a suitable depth into the tubing to gasify the oil column, and thus assist the production. Each... 

The development of alternative energy sources is a prominent area of scientific research. Hydrogen, with its exceptional energy density, has emerged as a particularly promising candidate among these new energy sources. An effective technique for generating hydrogen is through the electrochemical process of water splitting. To enhance this process, it is crucial to investigate the development of electrocatalysts with high electrocatalytic activity. Among the potential options, sulfides of transition metals show promise. An essential difficulty in electrochemical water splitting is the development of a bifunctional catalyst that is both active and stable for both the hydrogen evolution... 

Selective withdrawal is withdrawing water with desired quality from a reservoir and has many applications in water quality management of reservoirs. Topographic effects such as a sill alter the withdrawal layer properties. In this study, the effect of a sill on selective withdrawal of a two-layer fluid through a line sink at the bottom of a rectangular reservoir is studied using two-layer hydraulics theory, numerical model and laboratory experiments. Experiments were done for studying surge, and the results are compared with two-layer hydraulics theory and numerical model. After reservoir gate is opened, some disturbances upstream of sill lead to creation of a surge. The results show this is... 

In the current study, the dinuclear copper(I) complex ,[Cu2(μ-phthalazine)(phthalazine)2(μ-dppm)2](PF6)2,(1), has been prepared by the reaction of two equiv of [Cu(CH3CN)4]PF6, three aquiv of phthalazine, and two equiv of bis(diphenylphosphino)methane (dppm). However a mixture of two four coordinated copper(I) complex,1, and a three and four-coordinated copper(I) complex ,[Cu2(μ-phthalazine)(phthalazine)(μ-dppm)2](PF6)2,(2), have been prepared when the reaction has been carried out with equal ratio of the reactants. The structure of 1 and 2 determined using. X-ray crystallography in solid state and the structure of 1, further characterized by multinuclear NMR spectroscopy in solution.... 

In this study, the primary focus was on designing a novel drug scaffold aimed at inhibiting the HSP90 enzyme—an enzyme that, unlike many others, is intrinsically active and does not require upstream regulators for its function. This characteristic has made HSP90 a crucial therapeutic target in the treatment of various cancers and certain viral diseases. Recent studies have shown that the overactivity of this enzyme contributes to signaling pathways involved in cell proliferation, survival, and migration, and that its inhibition can arrest the growth of cancer cells.
To develop an effective compound for the specific inhibition of HSP90’s active site, a thorough examination of... 

By comparing the control systems, researcherstypically believe that the active systems of control have better performance than passive ones. However, the high costs and the required technology for their erection and maintenance have limited the use of active control systems. In order to improve the control system performance at lower costs, semi-active control systems were also considered. Their performance is based on creating the desired control force by changing the instrument characteristics.Moreover, recent researches have shown that the improved performance of these instruments in structures compared to passive control systems, are typically due to reducing the flexibility of the... 

A tensile-compression ring is derived from the spoke wheel principle. The wheel is one of the greatest inventions in mankind. The use of the wheel has developed through time. Engineers found out that the use of the spoke wheel as a roof structure provides many benefits. With the spoke wheel principle a lightweight, cost-efficient roof structure can be made. In recent years the spoke wheel principle has also been applied for oval shaped roofs in order to increase the application of the principle. An example is the use of the roof structure for football stadia. The problem is that the spoke wheel principle will only work at full extend when its shape is completely circular. The question rises... 

One important problem in query optimization in centralized and decentralized databases is optimizing queries containing common sub-expressions, known as multi-query optimization. In processing these queries, the goal is to process a group of queries together and find a global execution plan with minimum cost for the query set. In most of researches which have approached this problem the focus were on exhaustive algorithms. Since size of the problem space for these algorithms grows exponential with query set size, these approaches are impractical. In this research we have presented six algorithms based on Ant Colony Optimization metaheuristic. We have compared the efficiency of these methods... 

In most countries Frequency control services as one of the Ancillary services are presented in market scheme. Frequency control are used in different levels to balance generation and demand. Each reserve levels is implemented with specific characteristics and rules. Clearance of energy and one control reserve has some drawbacks so in this thesis we try to clear energy and different reserve levels simultaneously. Each reserve level is determined with special criteria. This criterion in primary reserve is frequency deviation restriction and unit commitment risk in territory reserve that is determined by system operator. In this thesis these two criteria are formulated in linear form and... 

The primary purpose of acidizing operations in the oil and gas industry is to enhance hydrocarbon production. Acidizing has been a common and conventional method for years, especially when production engineers face issues like declining reservoir pressure leading to reduced production rates. Initially, the treatment solution is referred to as matrix acidizing. In acidizing operations, different additives are combined with the acid to control its behavior in the reservoir. These additives may include iron control agents, corrosion inhibitors, friction reducers, and more. Incompatibility among these additives, the acid, and reservoir fluids can lead to severe damage to the reservoir.... 

The goal of this research is the simulation of the annular combustion chamber of the turbine engine utilized by liquid fuel. The achievement to this goal will lead to create numerical tools for parametric study, analysis and combustion chamber designing.For this reason simple geometry has been considered. This simplicity of geometry causes to facilitate in parametric study and decrease in saving time for modeling and meshing. This combustion chamber is a simplified model of engine CF6. In recent study, the k – ε realizable model has been used for turbulence modeling. For non-adiabatic condition, chemical reaction is dissolved by utilizing probability density function along with laminar...