Sharif Digital Repository

This study used the emulsion liquid membrane method to investigate the extraction and separation of thorium from nitrate solution. According to the results obtained from the studies, Cyanex 272 was a suitable option for selectively extracting thorium. For simultaneous extraction and stripping of thorium from dilute aqueous solutions, an emulsion liquid membrane system consisting of Cyanex 272 as an extractant, Span 80 as a surfactant and sulfuric acid solution as a receiving phase (internal phase) was used. Emulsion liquid membrane method has high mass transfer flux due to high surface to volume ratio, which causes high extraction efficiency and fast transfer of thorium ions from its low... 

One of the novel methods of stabilization of nuclear waste is the use of vitrification technology. In order to stabilize high level wastes (HLLW) in glass, it is required that the elements are in their oxide form. Therefore, it is necessary to evaporate the waste and turn it into a solid form so that the elements can be converted into oxide form in the calcination furnace. Hence, one of the challenges of stabilization is the optimization of evaporation and calcination conditions. In this research, the parameters affecting evaporation were first investigated. Using laboratory measurements of application: temperature (110 to 180 °C), presence of nitric acid (0.5 to 4 mol/L), ratio of zirconium... 

The subsidence phenomenon in the past years has caused many problems and issues for the agricultural lands, roads, power transmission lines, energy etc., due to different reasons including over use of groundwater resources and changes in climate. This phenomenon has been observed in different plains of the country including the Khorasan, Kerman, Hamedan, Ghazvin and Isfahan plains and has caused many damages to infrastructure and agricultural products in the mentioned regions. In this research the main factors which have affected the subsidence phenomenon especially reduced ground water table and climate changes in Ardebil plain, are taken into account and some studies which comprise... 

Innovations in laser, microwaves, and similar technologies have significantly advanced thermal treatments for diseases or even injuries concerning skin tissue. For a thorough understanding in the underlying mechanisms of bioheat transfer behavior of skin,a1D unsteady non-dimensional hyperbolic model of heat transfer through this tissue with metabolic heat generation which is subject to specific boundary conditions, is solved numerically using the finite difference method. A thermal shock is generated at the base of the tissue, which moves forward with a finite speed. A Numerical solution for a simple one-layer skin tissue is obtained. Then, the effects of various parameters, time step,... 

ADC is one of the key functional blocks of any mixed signal system and therefore must be optimally designed concerning power, performance, resolution and silicon area. Among different architectures have been employed up to now, successive approximation register ADCs are known as the ones with lower power, more simplicity and lower sampling rate. Benefiting from scaling down the CMOS technology results in higher sampling rate and lower power SAR ADCs replacing other types of ADCs. To achieve the desired ADC performance, efforts are usually focused on the improvement of circuit techniques as well as on the introduction of new or combinational architectures based on SAR ADCs. This thesis aims... 

The number of connected devices through the internet of things is increasing rapidly, which leads to adopting different communication technologies to provide connectivity of this large number of devices. The used communication technologies can be classified into the local area network, low-power wide-area network (LPWAN), and cellular network technologies. The receiver power has a critical role in the total power consumption of utilized transceiver chips in these technologies. Radiofrequency (RF) front-ends are often significant power-consuming parts of integrated receivers. Therefore, system-level design in which the overall specifications are distributed among RF front-end building blocks... 

Nowadays, customers hold a pivotal role as co-creators of value in service industries. Therefore, companies usually try to encourage customers to interact and co-create value effectively with the company or with each other. However, if a service provider fails to meet customer expectations, service failure occurs and may influence customer evaluations to co-create value. In this situation, companies usually try to redress the problem that happened to reduce their negative perceptions. Research related to the drivers of customers' value co-creation intentions has gained interest in recent years. However, there has not been an integrated view to simultaneously examine the negative role of... 

Nowadays, customers hold a pivotal role as co-creators of value in service industries. Therefore, companies usually try to encourage customers to interact and co-create value effectively with the company or with each other. However, if a service provider fails to meet customer expectations, service failure occurs and may influence customer evaluations to co-create value. In this situation, companies usually try to redress the problem that happened to reduce their negative perceptions. Research related to the drivers of customers' value co-creation intentions has gained interest in recent years. However, there has not been an integrated view to simultaneously examine the negative role of...