Sharif Digital Repository

Helium is known as a strategic material due to its unique properties and applications in the development of advanced industries. Currently, natural gas is the only source from which helium can be produced economically. The United States, Qatar, Algeria, and Russia have the largest share of helium production, respectively. In this research, the process of helium extraction from natural gas and its liquefaction, independent of LNG production based on helium in South Pars gas of Iran, which is the largest helium reservoir in the world, were designed and simulated.In the helium liquefaction section, the speed and accuracy of the process simulation were improved by developing a home code based on... 

Cryogenic temperature is below than 123 Kelvin and any physical study that occurs below this temperature is Cryogenic science. Cryogenic has varaiety of application in medical, industry, food, oil and gas etc. Based on this paper and its relavant source spiral wound HE is one of the most optimum HE for cryogenic application specially for helium liquification cycle. In order to liquefy helium in helium cycle efficiency of spiral wound HE shall be over than 85 percent. For this reason and special fluid behavour in low temperature considering property variation, heat in leak and axial conduction is vital for calculating efficiency in cryogenic temperature of helium liquification cycle. In this... 

Lateral spreading is the downstream movement of mild slopes or free fronts occurring due to soil liquefaction during a dynamic loading such as an earthquake. The magnitude of this movement can be from a few centimeters to tens of meters depending on parameters such as slope length, soil type, cyclic loading intensity, etc. Large displacements caused by this phenomenon can cause severe damage to some structures and infrastructures located in the direction of their movement. Numerous articles and reports of damage caused by the lateral spreading of soil have been presented during several earthquakes. Understanding this phenomenon and observing and testing its effective parameters can help... 

Lateral spreading is defined as finite lateral displacement of mildly sloping grounds or those ending in free faces induced by liquefaction. The phenomenon of lateral spreading caused by liquefaction in coastal areas and mildly sloping grounds has caused significant damage to deep foundations of engineering structures such as bridge and buildings in severe earthquakes. Since earthquake is unavoidable, therefore, it is necessary to provide appropriate solution to reduce the effects of liquefaction induced lateral spreading. Despite conducting various laboratory and field studies by previous researchers, there is still no comprehensive approach to evaluate the effects of lateral spreading on... 

Liquefaction is an important phenomenon in geotechnical engineering which can cause severe damages to structures. Liquefaction-induced lateral spreading is defined as the lateral displacement in mild slopes or level grounds ending in free faces (such as quay walls) triggered by liquefaction in subsurface soil layers. During recent years, extensive studies have been conducted around the world documenting liquefaction induced lateral spreading and its effects on deep foundations. In the present study, a series of shaking table experiments which were previously conducted at Sharif University of Technology are numerically simulated using the three dimensional finite difference based program,... 

This study aimed to model the cone penetration test using FLAC 2D software in order to investigate the silty soils that can be found in tailing dams. Additionally, the model of the direct simple shear test was built in the software to estimate the variation of liquefaction potential in these soils with in-situ conditions. It should be noted that the constitutive law used in this study was the NORSAND model which meets the requirements of modeling in both tests. After validating the models, several important parameters are considered as variables to examine their effects on the results of both experiments. Regarding the validation of the models, the constructed numerical models of the cone... 

There are several case history records of liquefaction in gravelly layers with more broadly-graded particles than uniform sands which have been typically examined. Liquified deposits, in many cases, were subjected to initial static shear stress associated with the sloping ground condition or the adjacent shallow foundations prior to liquefaction. There are several graphs and recommendations for practitioners to consider the effects of the initial static shear stress on liquefaction resistance in design processes, developed based on the results of experiments on uniform clean sands. However, data for the effect of the initial static shear stress on the liquefaction strength of gravelly soils...