Sharif Digital Repository

Collapsible soils are kinds of problematic soils which are susceptible to large and sudden reduction in volume upon wetting. A manifest kind of these soils is loess; catastrophic settlement of structures which are built upon it has been observed when the soil becomes wet. In this investigation the collapse potential of samples of loess taken from Gorgan, Golestan, Iran, has been studied by using unsaturated odometer tests under controlled matric suction. To this end, two modified odometer apparatus with the capability of controlling the matric suction, have been designed and developed. Undisturbed samples of soil have been tested under K0 condition, while the matric suction, volumetric... 

Considering the drastical increase of greenhouse gases in the atmosphere, especially carbon dioxide, reduction of these gases seems necessary to combat global warming. Fossil fuel power plants are one of the main sources of CO2 emission. In this paper, CO2 capture from a natural gas fired steam cycle power plant using oxy-fuel combustion technology is studied. The Integrated Environmental Control Model (IECM) developed by Carnegie Mellon University was used to evaluate the effect of this capture technology on the plant efficiency and economic parameters of the system. Since the oxygen production plant, CO2 capture and transport are cost and energy intensive, the cost of electricity generated... 

Due to the increasing influence of distribution generation , their effect in planning can't be ignord , especially solar panels ,which are incresing rapidly. The main purpose of this thesis is to an active distribution network that annually load bus and the amount of photovoltaic production in it increases and plan dynamically. In the planning that is done , uncertanty in the amount comsumption load and uncertanty in the pattern of sunlight and also annual innterest rates in the classical system we have planned by optimizing the network expansion costs , in addition to supplying the load bus, we can keep the voltage drop bus and line filling within the allowable . To do this , we considered... 

Determination of the elastic fields associated with a spherical multiply-coated inhomogeneous inclusion is a problem of great interest among researchers. In this work a set consisting of N+1 concentric spherical domains is considered. Each domain is either isotropic or spherically isotropic and is functionally graded (FG) in the radial direction. The outermost spherical surface is subjected to nonuniform loading and the constituent phases are subjected to some prescribed nonuniform body force and eigenstrain fields. When the outermost domain is an unbounded medium with zero eigenstrain and body force fields then an N-phase multi-inhomogeneous inclusion problem is realized for which the... 

Millions of people are exposed to noise every day in their work and life, and their physical and mental health is at risk due to this issue. Hence, the issue of noise and vibration has become an important factor in car quality. One of the sources of noise and vibration in the vehicle is the engine. The engine is the heart of the car and its most important part. Therefore, reducing Engine noise can have a significant effect on the noise emitted by the vehicle. Engine noise can be divided into three categories: 1 - combustion noise 2 - mechanical noise 3 - aerodynamic noise. This project is in line with a project defined between the university and industry aimed at improving all sources of... 

NiTi Memory alloys have a great range of applications. Porous metallic biomaterials (e.g., stainless steel, chromium- cobalt, titanium and nickel–titanium (NiTi)) represent superior alternatives to traditional non-porous metallic implants for two main reasons. First, open porosity can enhance bone ingrowth and thus improve fixation at the interface between bone and implant. Second, porosity decreases the mismatch in stiffness between bone and implant, thus reducing stress-shielding effects which shorten the lifetime of the implant through bone resorption and loosening. NiTi foams may thus find multi-functional applications such as bone implants, impedance-matching connectors between... 

Despite the increase in the number of cardiovascular diseases worldwide, the number of new drugs to treat these diseases has been decreasing in the last decade. Current preclinical drug evaluation strategies, which use cell cultures and oversimplified animal models, cannot meet the growing demand for new and effective drugs. In the last decade, the development of microfluidic bioreactors and organ-on-chip systems to improve the drug screening process has been increasing significantly. These systems have shown many advantages over previous preclinical models. Despite all these advantages, keeping the oxygen concentration at the optimal physiological level in microfluidic systems has its own... 

Air-cooled condenser is widely used in thermal power plants as its main cooling system. However, the thermal capacity of air-cooled condensers reduces considerably in environmental wind drafts. So, the purpose of this study is to find practicable solutions to minimize the mal-performance of air-cooled condensers in windy conditions in either design or off-design conditions and consequently prevent the related steam turbines power reduction. The target combined cycle power plant consists of 4*160 MW steam turbines and 4 air-cooled condensers in its steam cycle part. This research presents two general and practical remedies, which are also applicable to many different powerplants irrespective... 

In the proton exchange membrane fuel cells (PEM, the produced water would be divided into two phases of vapor and liquid. distribution of both liquid and vapor phases in different cell layers affects the performance, the efficiency and the life of a fuel cell significantly. Moreover, Nano pores of the cathode catalyst layer are involved with some phenomena such as electrochemical reaction kinetics, heat and mass transfer and interface phase change. One of the most important problems in the performance of fuel cells is distribution of liquid water in the porous areas. Water flooding in fuel cells causes to delay in oxygen transport to active sites in the catalyst layer because the pores of... 

The propagation behavior of Love wave in functionally graded magneto-electro-elastic half-spaces with a quadratic variation is addressed. The magneto-electromechanical coupling factor, the dispersion relations, electric potential, magnetic potential and displacement are obtained analytically for both magneto-electrically open and short conditions. The effect of gradient coefficient on phase velocity, group velocity and magneto-electromechanical coupling factor are plotted and discussed. Research on the wave propagation in magneto-electro-elastic materials is still very limited. This work provides us with a theoretical foundation to design and practically apply SAW devices with high... 

In this study, the interaction between thin plate completely bonded to the transversely isotropic halfspace and a concentrated force applied horizontally (Mindlin-type force) are considered. This problem has been solved analytically. This problem is used as sample for thin solid films and surface coating technology, where the surface of solid is covered by thethin plate for increasing its stiffness. Moreover, this problem is a good sample when homogenous solid is subjected to contact loading and can be seen that mechanical properties of material which is near the solid surface varies; consequently, a two-phase solid is created.Because of the influence of noted inhomogeneity, solid is... 

Hydrodynamics plays a crucial role in defining the performance of fluidized beds. The numerical simulation of fluidized bed is very important in the prediction of its behaviour. From this point of view, in the present study a dynamic two dimensioanl model is developed for the modeling of regenerator system of a UOP fluid catalytic cracking (FCC) unit of Abadan refinery with a high-efficiency regenerator. Of the various modeling and simulation techniques, computational fluid dynamics (CFD) is employed in this thesis. Effects of gas velocity, the transient local solid volume fraction, pressure drop for gas and solid phase, solid holdup distribution and solid circulation pattern have been... 

Privacy preserving data mining helps organizations and companies not only to deal with privacy concerns of customers and regular limitations, but also to benefit from collaborative data mining. Utilizing cryptographic techniques and secure multiparty computation (SMC) are among widely employed approaches for preserving privacy in distributed data mining. The general purpose of secure multiparty computation protocols to compute specific functions on private inputs of parties in a collaborative manner and without revealing their private inputs. Providing rigorous security proof of secure multiparty computation makes it a good choice for privacy preservation, despite of its cryptographic... 

The rapid growth of Android operating system alongside its open-source nature has made it as the most popular operating system of mobile devices. On the other hand, regarding the increasing computational power of mobile devices, a wide variety of applications are coming to this type of devices. Meanwhile unfortunately many malicious softwares trying to keep up with other applications, are targeting this popular operating system. Therefore with regard to the fact that this type of devices usually store private and sensitive information of their users, security of mobile operating systems is considered very important. Having this matter in mind, the goal of this research work has been... 

In this study, a new concrete slab stiffened by concrete pedestals and steel cables is introduced. The slab system is studied by employing both analytical and numerical methods. The steel cables are connected to the edges of slab and the concrete pedestals mounted at the bottom face of slab act as the middle supports of cables. The tension force in the cable and its inclination results in upward forces acting at the bottom face of slab. With the aims of classical theory of thin plates and the superposition technique, the problem of a simply supported rectangular slab stiffened by cables is studied analytically. The obtained results are verified by a numerical modelling implemented in SAP2000... 

The parametric study of a new introduced metallic yielding damper called telescopic damper is addressed. The telescopic damper comprises of three concentric steel pipes connected together by lead shear keys. The inner and outer steel pipes are subjected to axial loading which results in the shear yielding of the embedded lead cylinders. The inner steel pipe has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Employing ABAQUS software, the behavior of damper under cyclic loading is studied numerically. The finite element model is verified by available results in the literature. The effects of inner and outer steel pipes thickness,...