Sharif Digital Repository

The simplest definition of Total Factor Productivity is the rate of converting inputs to outputs. In other words, with fixed inputs and a raise in the Total Factor Productivity, more output can be achieved. In this study, we review the existing methods for calculating this variable and its determining factors. On the basis of Diewert’s criteria, Fisher index is known to be the most appropriate indicator to calculate production, price and productivity indices. Fisher index is obtained by dividing the index of output to input in which in addition to values of output and input, price data are also used. Between prices and values used in this calculation only price series for wages are not... 

Implementation and development of large infrastructure projects are considered as the most important tools for governments to achieve sustainable development. Need of enormous finance, high level of technology and massive workload are the main feature of these projects. These projects cause significant effects on economic, technological and even political and social status in nations. So the appropriate project delivery method selection is very important for the preparation and implementation of this kind of projects. Also, mistake in this field will bring irreversible costs and losses.
Thus, the appropriate policy in decision making process about the project delivery method... 

Nowadays, a wind tunnel is a tool used in aerodynamic research to study the effects of air moving past solid objects. By employing a wind tunnel, we can compeletely control the conditions of aerodynamic testing on specific models. In this research, the design of a diffuser for the subsonic wind tunnel has been taken into account by CFD. The wind tunnel is of suction type and is powered by three axial fans which are manufactured by LTG Inc. The tunnel test section has a 140 cm height and 195cm width which can provide a necessary Mach number. Considering the setting of the three axial fans, located at the end of the diffuser and parallel to each other, it’s necessary to take into consideration... 

Progress of technology and the ability of construction of devices in micro and nano scales, have developed a new field of science that the classical laws of fluid dynamics can not be analyzed in by the well known Navier-Stokes Model. So, research fields in micro and nano scales have been paid attention more. In micro and nano scales, due to small size of characteristic length, the fluid is rarefied and the behavior of the fluid and its interaction with surfaces and walls in such scales is very different from those in large-scale systems. So, the particle-based-methods like Direct Simulation Monte-Carlo (DSMC) method have been considered one of the most interesting fields of researches for... 

This research considers the wind effects on the thermal deficiency of natural draught dry cooling tower (NDDCT) using the CFD tool. To have a realistic study, the NDDCT of Shazand Powerplant, located in Shazand, Iran, is simulated as the sample cooling tower design points. Considering of Shazand NDDCT model, the mal-effects of local wind were studied against its thermal efficiency. As is known, the thermal efficiency of a NDDCT can be affected by local wind in either its upper (i.e., outlet section) or lower (i.e., the radiator section) parts. In this study, a full study is performed to quantify the mal-effects of local wind on either upper or lower parts of one tower. The results show that... 

Maintaining the quality of water is of paramount importance for lakes with tourist attraction capacity. Inaccurate prediction of the quality state of lake in design phase may lead to some trouble in future. Kan River known as the main source of water feeding for the urban lake located in the north of Chitgar park passes through various villages and restaurants discharging nutrients via runoff and wastewater in the aforementioned river. Previous investigations reveal that phosphorous plays a central role in the water quality of this river and the associated downstream lake. In this research, Kan watershed,located in in the north-west of Tehran, was simulated. Considering the "Total Maximum... 

The Response modification factor R represents the behavior of the structure such as ductility, overstrength and the inherent redundancy. This factor shall be defined according to the type of lateral force resisting system. However, there are some complexities and/or uncertainties in codes related to the R factor according to the height, form of irregularities and structural systems. Therefore, from the scientific point of view as well as reliability, it is very clear that the R factor cannot be similar for all kinds of structures, categorized as a specific group. In this investigation, assuming a low-rise, vertically irregular structure with a heliport which has a dual structural system... 

In this project, we are willing to analyze and design a subsonic wind tunnel WT configuration for the Aerospace Engineering Department in Sharif University of Technology. This WT will be an open-circuit "suck down" type, whose entry is open to the atmosphere (laboratory) and three axial fans downstream of its test section. In addition to three parallel fans, we are expected to design two simultaneous small and large size test sections for it. The small and large sections would have an area about 1.4 and 4 m2and maintain a maximum air velocity of 100 and 50 m/s, respectively. So, our design is faced with two main complexities. In one hand, we are to manage the air flow through these two test... 

Exchange rate is one of the macroeconomic variables that can affect domestic product, economic growth and unemployment. Since macroeconomics wants to explain inflation, unemployment and economic growth, exchange rate is one of the most important macroeconomic variables. In economic literature, many studies have been performed to investigate the linkage between Real Exchange Rate (RER) and other real economic variables (such as domestic product, unemployment, etc.). In this study, we first construct the RER for the economy of Iran and then, using Vector Error Correction Model (VECM), short-run and long-run relations between RER and Gross Domestic Product (GDP) is evaluated.
The results of... 

Tall building development has been rapidly increasing world wide introducing new challenges that need to be met through engineering judgment. In modern tall buildings, lateral loads induced by wind or earthquake are often resisted by a system of coupled shear walls. But when the building increases in height, the stiffness of the structure becomes more important and introduction of outrigger beams between the shear walls and external columns is often used to provide sufficient lateral stiffness to the structure.In general, earthquake ground motion can occur anywhere in the world and the risk associated with tall buildings, especially under severe earthquakes,... 

The low performance of the natural resource economies in terms of economic growth has been considered in different fields of social sciences recently. Variety of policies suggested escaping from this phenomenon with respect to different standpoints. In this research, based on a theoretical approach, we tried to model the leader and people’s behavior in resource rich countries with political economics viewpoint and rational players. The contribution of this research is the introduction of state owned enterprises (SOE) as a basis to resource curse, which has not been considered precisely before. In our model, we have two players (leader, people), two alternatives for resource allocation... 

In this thesis, a dynamic stochastic general equilibrium model under new-Keynesian assumptions has been proposed for the economy of Iran, as a major oil-exporting economy. The economy is supposed to be inhabited by households, firms (both final-good and intermediate-good producing firms), a government and a monetary authority. It is exposed to stochastic and exogenous shocks to total factor productivity, oil export revenues and the growth rate of money. The most important features of the model, which distinguish it from most other proposed models for the economy of Iran, are the assumptions of the presence of monopolistic competition in intermediate-good producing firms and also a degree of... 

In this study, a new finite-element-volume (FEV) arbitrary Lagrangian-Eulerian (ALE) method is suitably extended to simulate the three-phases flows air, liquid water droplets and ice in ice accretion, i.e., over flying object surfaces. This methods benefit from the advantages of both finite-volume and finite-element methods. This method is developed for the first time to simulate three phases turbulent flows. Since the ice formation and growth needs grid movement consistant with ice boundary movement, we have used ALE approach to fulfill this requirment. In this regard, we use the linear spring analogy approach to move the hybrid triangular-rectangular mesh suitably. Facing with a chaotic... 

Many efforts have been performed on the poly(vinylidene fluoride), PVDF, due to its piezoelectric, pyroelectric and ferroelectric potentials. In this thesis Poly (vinyldene Flouride) (PVDF)/Poly (vinyl Asetate) (PVAc)/Multi-walled carbon nanotubes (MWCNT) and Poly (vinyldene Flouride) (PVDF)/Poly (vinyl Asetate) (PVAc)/Graphene Oxide nonasheets (GOn) nanocomposite films were prepared via solution casting method. The effect of concentration of PVAc, MWCNT and graphene oxide on PVDF nanocomposites were investigated. Graphene oxides synthesized by modified Hummer’s method. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results showed that the crystalline structure of... 

This thesis presents the development of a Finite Element Model (FEM) for a new type of Beam-Column Semi-Rigid steel connection. This connection consists of a steel semi cylinder connected to a plate and inserted on the top and bottom of the beam connecting it to the column by welding. It seems that changing the geometry of the semi cylinders and their weld lengths can have a great influence on the rigidity or flexibility of the connection. Therefore, meaningful categories of the connection with different semi cylinder geometries and weld lengths have been modeled and investigated by means of a Finite Element Modeling software ABAQUS, and their moment-rotation curves were driven. Also the... 

The enviromental wind would cause serious drop in the performance of Heller cooling systems in thermal powerplants working on Rankin cycle. Therfore, it is necessary to consider the wind velocity in the design of such cooling tower systems. We use the computational fluid dynamics (CFD) and simulate the 3D buoyant flow passing through and over a heel cooling tower. We consider three different wind veocities of 0, 5 and 10 m/s in our simulations. In order to consider the low efficiency of the cooling system in efficiency drop of the main rankin cycle, we need to consider actual power generated by the powerplant generator, which is directly affected by the turbine back pressure. To connect the... 

In this study, our objective is to simulate the growth of frost for humid air passing through pressure regulators. The study is carried out in two main stages. First, we use an empirical method to model the formation of frost for a humid-air passing over a flat plate. The model is a semi-2D one and that it is limited to predict the frost growth at a particular station along the plate, considering the local flow heat transfer parameters. We show the validity of results comparing with available experimental data. Second, we numerically simulate the frost formation and growth for a humid air passing between two parallel plates. In this regard, the semi empirical method is suitably coupled with... 

Evaporation is the initial process of losing water and heat from the surface of the lake. There are six well-known methods for estimating the evaporation of water from surface water including: the water balance method,the energy balance method, themass transfer methods, the combined mass transfer and energy balance method, the empirical equation and using pan evaporation. In this thesis, evaporation has been calculated with using different equations, in-site observation and remote sensing data. These results also have been compared with the results of the energy balance method. In addition, we have developed modified empirical equations of fresh water evaporation estimation with the... 

In this work, magnetite (Fe3O4) nanoparticles with an average siz21.9nm
modified by oleic acid were prepared by the coprecipitation method, which can linked well with organic molecules because of the presence of C-O-C on their surface. Then magnetic poly(lactic acid) (PLA)/ poly(ethylene glycol) (PEG) microspheres were prepared by the single emulsion solvent evaporation technology. The incorporation of magnetit nanoparticles and dox into the PLA matrix was confirmed by FTIR. XRD and VSM confirmed the existence of MNPs in the microspheres which maintained superparamagnetic behavior with a saturation magnetization of 50.69 emu/g.Electron microscopy SEM showed that the magnetic microspheres... 

Evaporation is the most important water loss from terminal lakes which can influence the chemistry of lakes. In large lakes, the spatial distributions of meteorological and water quality variables affect the evaporation rates. Therefore, it is crucial to consider such variations in estimating evaporation rates from large lakes. This study aims at developing an evaporation estimation model for saline lakes considering salinity and spatial distribution of variables in/over the lakes and investigating the interaction between meteorological, hydrological and water quality variables in natural saline systems. To accomplish these objectives, first a distributed model was developed for estimating...