Sharif Digital Repository

Dynamic analysis of deploying elastic arms of spacecrafts carrying tip mass has been presented. The research concentrates on the precise analytical simulation to reveal the phenomena which are usually eliminated in estimations. One of the most important factors which affect the dynamic response of such arms is rigid body dynamics of spacecraft. Considering this aspect of the problem the evolutionary analytical simulation has been developed through three steps. The first step focuses on the minute simulation of the arm deployment, in which a new mathematical approach called "elastic profile" has been developed which leads to semi-analytical solutions for the arm carrying tip mass.... 

The water crisis in Iran is not only caused by climatic changes, in other words, human factors have also influenced the increase in water consumption. The intertwining of various economic, political, and social factors has caused a direct and dynamic impact on water resources. Undoubtedly, one of the most important processes in policy-making and in the continuation of planning the country's water resources is the approval of useful laws from the point of view of implementation, monitoring and finally having a positive impact on the subject under discussion. From this point of view, the main research question is the role of laws on the current state of water resources management. The first... 

Communication Buoys are devices that facilitate radio communication between underwater ships and surface stations. In this research such device is thoroughly designed for a submersible application. The system comprises of buoy, connection cable, buoy cavity, cable passage, winch and other supporting and safety subsystems. Buoy and cable system was analyzed in a general form and their stable states were determined for different ship maneuvers, sea streams, and wave conditions. Based on this, optimum buoy geometry and cable length were found for the defined application and other subsystems were detail designed. To evaluate the design, some of the system components were manufactured and... 

Correlation-intractability is a random-oracle-like property of hash functions, so one can expect that constructions that are secure in random-oracle-model, remain secure when implemented using a correlation-intractable hash function. This is true about Fiat-Shamir transform which is a method for eliminating interaction from public-coin interactive proofs. One can see that when this method is applied to a public-coin three-round honest-verifier zero-knowledge proof, using a correlation-intractable hash function that also satisfies some mild assumption, the result is a NIZK argument. This is the basis for the correlation-intractability framework for NIZK which recently has been used to... 

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... 

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 most common spinal surgeries involves spinal fusion or vertebral fixation, which is used to treat various conditions such as intervertebral disc disease, scoliosis (lateral deviation of the spinal column), fractures, infections, or the presence of tumors in the spinal column. In this surgical procedure, the use of pedicle screws and titanium rods prevents motion and friction between two vertebrae. Screws may enter the vertebrae in the wrong position and angle, causing bone weakening, rupture of nerve roots or blood vessels, weakness or lack of sensation in some parts of the body, spinal cord injury, and in severe cases, paralysis of the patient. For this reason, fusion surgery is... 

Lithium is a soft, silvery-white alkali metal that is recognized as the lightest metal and the least dense solid element. The increasing demand for lithium, driven by the global shift towards electrification and sustainable energy solutions, has transformed this material into a crucial resource in the modern economy. Lithium has applications in various industries, including the nuclear industry. 6Li is used for the production of tritium, and 7Li, in the form of 7LiOH, is used to adjust the pH in light water reactors and as an anti-corrosion compound in fission reactors. In this study, the extraction of lithium from the aqueous phase using a Y-shaped microchannel was carried out, and the mass...