Sharif Digital Repository

Considering the widespread applications of amides, synthesis of these compounds is of great importance. The one pot oxidative addition of amines to aldehydes is one of the most simple and appealing approaches to synthesis amides. With the aim of developing a mild and convenient approach towards preparation of amides, numerous methods have been reported for this important process over the past few decades. These improvements have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including diverse derivatives of aldehydes, and also design a novel and effective catalytic systems. Due to the various advantages of supported heterogeneous... 

With the aim of making a pilot in two-steps, this thesis at 4 month accomplished. In first step, municipal sewage after passing of a septic tank loaded with daily 2 or 4m3/m2 rate to a vermi-filter while removal rate of COD was 83 and 64 percent respectively. In addition, the turbidity removal rate was 92 and 83 percent respectively. The results showed that vermi-filter is a suitable and cheap way for on-site wastewater treatment that is environmentally agreeable and odorless. Furthermore, the treated sewage is suitable for irrigate and flush tank usage. In the second step, for ground water denitrification, a synthetic wastewater with high nitrate, which nitrate is initially 13.5ppm NO3-N... 

Selective laser sintering is a technique which uses a laser as the power source to sintering some selected points at a bed of powder in order to create a solid structure. In this research the SLS mechanisms of powder deposition is simulated and surface smoothness and layer density created by each mechanism is computed. For this purpose roller, blade and hopper mechanisms are simulated. For this simulation, polyamide 12 (PA2200) which is a common material is used. In this simulation at first powder specifications are extracted according to the references and for particle shape instead of using the spherical particle shape we use a certain shape that is more close to reality which created by... 

This study was conducted to investigate a theoretical and experimental two-dimensional model of a floating fish cage in regular waves and uniform current. Due to the inefficiency of computational fluid dynamics (CFD) in solving such problems, developing a simple model to predict the results is highly advantageous. In this study, a simple mass-spring model was developed to simulate the problem. After validating the results of this simple model through a series of model tests in a wave tank, it was further utilized to extract additional results. Experiments were conducted at six different wave heights and four current velocities. In all experiments, wave steepness was maintained at a ratio of... 

Global energy consumption is on a trajectory to surge by 50% by 2050, primarily driven by prevailing energy consumption patterns. Consequently, the imperative to innovate and develop novel energy sources, such as the utilization of recycled waste heat, has become paramount for the foreseeable future. In light of this, this paper delves into the transformative potential of employing Phase Change Materials (PCMs) for cooling Thermoelectric Generators (TEGs) and harnessing waste heat for productive purposes. The research investigates three distinct configurations to evaluate the efficacy of PCMs in enhancing thermal management. Configuration 1 exclusively relies on an active cooling fan, while... 

Mechanical behavior of tissue engineering scaffolds plays a key role in their biological performance; however the effect of microstructural features on mechanical behavior of such scaffolds is still under investigation. The objective of this study was to investigate the influence of pore architecture and relative density on mechanical behavior of rapid prototyped scaffolds. In this regard, scaffolds with different cubic, hexagonal and trigonal unit cells were designed. These unit cells were repeated in different arrangements in 3D space to produce different nodal connectivities. The internal dimension of pores varied from 500 to 600 μm. Plastic models of scaffolds then fabricated by 3D... 

In the current research, colloidal stability of two different types of coating on the surface of Superparamagnetic Iron Oxide nanoparticles (SPIONs) was studied. In the first triumph, a dual-layer coating was achieved by utilizing optimum amount of Dextran and different PEG (Poly(ethylene glycol)) concentrations which the weight ratios of iron oxide/PEG were 1/1, 2/1, 4/1, 8/1, and 16/1. Then, the presence of the coating was characterized by XRD, FT-IR, DLS and FE-SEM methods. These results together with the TGA ones revealed that as the concentration of PEG surfactant increases, the thickness of coating increases. Moreover, VSM test was performed to specify the effect of coating on the... 

In recent years, the widespread investigation on multi-transition metal oxides that with two or more transition metal oxides, have been increased rapidly for electrochemical application due to low cost, high conductivity and good electrochemical performance other than single metal oxides. In this project, CuCo2O4 nanoparticles were firstly fabricated by decomposing of CuCo-MOF as the template. The as prepared samples were used to synthesis a new nanocomposite of MoS2 and CuCo2O4. The best ratio of the two component were optimized to prepare the best electrocatalyst for Hydrogen evolution reaction (HER). The structure of prepared nanocomposite were investigated by various techniques such as... 

The integrative supply chain management is one of the main business processes between final consumer and supplier and it is formed by responsibilities such as production, services and information those have added value for customers and beneficiaries. Therefore and as the goal of a chain is maximization of gained value for the factors involved in chain, so, this goal can be more accessible by decreasing transportation (transportation method, tracking, …) and stock costs (conservation, ordering, …). As its purpose, this thesis intends to introduce and increase the options of goods transportation possibilities between retailers’ warehouses and evaluation of its effect on transportation and... 

Fog computing environment consists of several devices which distribute across an arbitrary topology. Each of these devices is capable of carrying out a designated computation simultaneously with other devices. One of the common ways of describing a computation is through the usage of workflows. Workflow is a flexible and formal way of modeling tasks and their requirements for execution. A workflow is essentially a DAG. Therefore, it can model the data dependency between tasks quite accurately. The complex structure of a workflow in conjunction with the homogenous nature of devices in a fog environment makes it difficult to find a resource management algorithm to minimize execution time, used... 

The ultimate aim of this research is optimizing high- performance Horizontal Axis Wind Turbine (HAWT) associated with using Computational fluid dynamics (CFD) to predict the flow behavior over wind turbine blades. Computational prediction of the flow over wind turbines is a challenging numerical problem because of the complicated aerodynamics and large variation in length scales. Phenomena such as; the unsteady flow, vortex shedding of the blade tips, flow separation, complicated blade geometry due to variable twist and chord and changes in angle of attack, and highly turbulent flow over blade sections makes CFD prediction challenging, as well as interesting. The goal is to gain an in depth... 

Considering the widespread applications of α-aminonitriles, their synthesis is of great importance. The Strecker reaction represents a direct and appealing approach for the preparation of α-aminonitriles. With the aim of developing a mild and convenient approach towards the construction of α-aminonitriles, numerous methods have been reported for this important process over the past few decades. These have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including ketimines and ketiminium salts and design of novel and effective catalytic systems. Due to the various advantages of supported heterogeneous catalysts and in our aim to... 

In this study, using the B3LYP/6-3111++g(d,p) computational level, we have explored the possibility of formation of some organic and bioorganic cation-cation clusters (CCC) in the absence of any anionic stabilizing species. Furthermore, we have shown the existence of a barrier energy for exothermic dissociation of these clusters. Herein, we have selected some biomolecules such as the chloroquine (CQ) antimalarial drug . The selected molecules possess the basic sites and can function as both hydrogen bond donors and acceptors. Also, a facile and direct synthetic route toward the rhodanine derivatives and thiazolidine-2,4-diones via a three-component coupling of carbon disulfide, primary... 

This project focuses on the design of fuel drop tanks for airplanes that add minimal drag and positive lift to the flying object. This will obviously effect the stability and dynamic performance of the airplane. To reduce adverse dynamic effects the tank was divided to several segment with a special emptying sequence. The add-on tank has to have no interference with the object existing systems and require minimum structural changes in the object. Several designs were proposed and the one gaining highest marks was selected. The flow field and the dynamic behavior of combined vehicle and drop tanks were studied using FE simulations. The result shows that adding a drop tank with optimized... 

This study considers blood flow in total cavopulmonary connection (TCPC) morphology, which is created in Fontan surgical procedure in patients with single ventricle heart disease. Ordinary process of TCPC operation reduces the pulmonary blood flow pulsatility; because of right ventricle being bypassed. This phenomenon causes a lot of side effects for patients. A cardiac surgeon has suggested that keeping main pulmonary artery (MPA) partially open, would increase pulmonary flow pulsations. MPA gets closed in ordinary TCPC operation. The purpose of current study is to verify the effects of keeping MPA partially open on pulmonary flow pulsations, by means of computational fluid dynamics (CFD).... 

Offshore platforms are one of the most important structures in oil-rich countries, so that their economic benefit makes it very expensive to stop their usage. Therefore, it is essential that their performance is not disrupted by earthquake or the tidal waves made by severe storms. In the conventional bracing systems, it is assumed that the braces buckle under compressive forces; but Buckling Restrained Brace (BRB) does not buckle under pressure. In this study performance of BRB in jacket platform, with a case study of Resalat platform, has been investigated under earthquake load and powerful wave. The modeling of jacket equipped with this brace has been done in Abaqus software, and results... 

Solid oxide fuel cell (SOFC) is one of the promising candidates for clean energy production. Due to the high operating temperature of SOFC, a protective coating is commonly applied on the surface of interconnects to prevent oxidation. In this study, electrophoretic deposition was employed to prepare a manganese-cobalt spinel coating on the surface of ferritic stainless steel (AISISAE430) substrates. MnCo2O4 powder with an average particle size of 60 nm was utilized and the sintering behavior of the coatings at different temperatures was studied. Non-isothermal and isothermal sintering behavior of the powder compacts were examined by employing a sensitive dilatometer. Master sintering curve...